Modern dial-up modems typically have a maximum theoretical speed of 56 kbit/s (using the V.92 protocol), although in most cases only up to 53 kbit/s is possible due to overhead and FCC regulation. These speeds are currently considered the maximum possible; in many cases transfer speeds will be lower, averaging anywhere between 33-43 kbit/s. Factors such as phone line noise and conditions, as well as the quality of the modem itself, if the modem is external or internal, all play a large part in determining connection speeds.

Dial-up connections usually have high latency that can be as high as 200 ms or even more, which can make online gaming or videoconferencing difficult, if not impossible. Some games, such as Star Wars: Galaxies and The Sims Online are capable of running on 56 K dial-up. Gamers with dial-up connections are often disconnected from game servers due to the "lag", or high latency, of the connection. (Wikipedia)

Sources & Additional Information:
Wikipedia

A modem. You purchase a modem for $15-100 depending on features and types. Most, if not all computers bought today come with 56K modems standard.

If your low on power outlets, go with an internal PCI based modem(56K). Otherwise buy an external modem, for they are much easier to troubleshoot when problems arise! Also, you won't need to power cycle (reboot) your PC when you do need to reset the modem which must be done with all internal modems usually.
awolfpup

300 bit per second - 1960s through 1983 or so
1200 bit per second - gained popularity in 1983 - 1985
2400 bit per second - arrived early 1985
9600 bit per second - US Robotics 9600 intro Comdex, 1986
14.4K bit per second -
19.2K bit per second -
28.8K bit per second - 1994
33.6K bit per second -
56K bit per second - became the standard in 1998

howstuffworks.com

An internet service provider (abbr. ISP, also called Internet access provider or IAP) is a business or organization that offers users access to the Internet and related services. In the past, most ISP's were run by the phone company. Now ISP's can be started by just about anyone. They provide services such as Internet transit, domain name registration and hosting, dial-up or DSL access, leased line access and colocation. (Wikipedia)

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Wikipedia

Windows 95/98/ME:
1. From My Computer open up Dail-Up Networking. In Windows ME this is located in Control Panel.
2. Open up Make New Connection
3. Give the connection a name.
4. Type in the access number. Leave the area code blank if it is not necessary to dial the area code.
5. Click Finish.
6. Here you will see your new connectoid. Right-click on it and select Create a shortcut and then select Yes on the error to make a shortcut on the desktop.
7. Open up the connection and type in the username and password.

Win NT:
1. Double Click on Dial-up Networking.
2. From the drop-down menu you can select to connect with a dialer that's already been created. If you click dial you will get the second screen. Type in the username and password. Or you can click on new button to create a new phonebook entry
3. Type a name for your connection.
4. Click on the first two-checklist boxes. Click Next.
5. Type in the access number. Leave the area code blank if it is not necessary to dial the area code.
6. Click finish to complete.
7. Type in the username and password.

Win 2k:
1. Click the Start menu, Settings, then Network and Dial-Up Connections. Network and Dial-Up Connections can also be found in the Control Panel.
2. Open up Make New Connection.
3. Choose Next.
4. Choose the second option, "Dial-up to the Internet".
5. Choose the third option, "I want to set up my Internet connection manually, or I want to connect through a local area network (LAN)."
6. Choose the first option, "I connect through a phone line and a modem".
7. Type in the access number. Leave the area code blank if it is not necessary to dial the area code.
8. Type in the username and password.
9. Give the connection a name.
10. Select the second option, "No".
11. Click finish.
12. Here you will see your new connectoid. Right-click on it and select Create a shortcut and then selct Yes on the error to make a shortcut on the desktop.
13. Open up the connection and click Dial.

Win XP:
1. Open up Control Panel. If it says, "Pick a category" or on the left says, "Switch to Classic View" then click on "Switch to Classic View".
2. From the Control Panel in Classic View open up Network Connections.
3. On the left select "Create a new connection." There may be some situations where that option is not available. If the arrows to the right of Network Tasks are pointing down then click on them and they will point up and the option will become available. Under other circumstances there will be no options on the left. In that case click on the File drop-down-menu and then select New Connection.
4. Choose Next.
5. Choose the first option, "Connect to the Internet".
6. Choose the second option, "Set up my connection manually".
7. Choose the first option, "Connect using a dial-up modem".
8. Give the connection a name.
9. Type in the access number. Do no type in the area code if it is not necessary to dial the area code.
10. Type in the username and password. Some people prefer to take the check mark out of the third box, "Turn on Internet Connection Firewall for this connection." Take the check mark out of the second box, "Make this default Internet connection" if you user usually uses another connection or usually uses this computer for DSL.
11. Put a check mark in, "Add a shortcut to this connection to my desktop" .
12. If you are ready to dial now click on Dial. Otherwise choose Cancel
13. This new connection can either be accessed under the Dial-up section in Network Connections or via the shortcut on the desktop.

Mac OS8:
1. From the Apple menu choose Control Panel then FreePPP Dialer.
2. Choose the arrow in the bottom left to get the expanded options.
4. Go to the accounts tab and click new.
5. Give the connection a name. Type in the username and password.
6. In the Dialup tab type in the access number. Leave the Dial area code box blank if it is not necessary to dial the area code. Enter in alternate numbers if available. Click on OK.
8. In Connect to: select the account that you just created. Select the proper location properties and modem. Click Connect.

Mac OS9:
1. Open the Remote Access control panel.
2. Click the radio button for Registered User.
3. Type the user name, password, and phone number into the corresponding fields. If you want your password to be saved so that you do not have to enter it at each connection, select the checkbox for "Save password".
4. Instead of opening up the Remote Access Control panel every time you can just open the Control Strip, and locate the Remote Access portion, which is labeled with the icon of a Macintosh computer over a telephone pole. If the Control Strip is not visible, open the Control Strip control panel and select Show Control Strip.

Mac OSX:
1. From the Apple menu choose System Preferences.
2. Select Network and then under location choose New Location.
3. Type in a name for this connection.
4. In show select Modem Port. In the TCP/IP tab make sure Configure has Using PPP selected. You can force DNS here if you want also by typing in the DNS servers in the Domain Name Servers box.
5. In the PPP tab make type in the username and password. Type in the access number. Do not type in the area code if it is not necessary to dial the area code.
6. Click on PPP options. Put a check only in send PPP echo packets and Use TCP header compression. Configure Session Options according to personal tastes.
7. In the Modem tab you can select the modem and configure the dialing options.
8. Open the MacintoshHD then open Applications.
9. Open up Internet Connect.
10. Under configuration select either the name of the connection or Modem Port and then Connect.

"What is often advertised as "high-speed dial-up Internet" or "accelerated dial-up" by service providers such as Earthlink and NetZero in the United States is a form of dial-up access that utilizes the newer modem standard v.92 to shorten the log-on (or handshake) process, and then once a connection has been established the provider will selectively compress, filter, and cache data being sent to the users home with the overall effect of increasing the speed of browsing most standard web pages (see also proxy server).

The term high speed is misleading as these processes do not increase the overall throughput of the line, only making more efficient use of the bandwidth that is already there. Certain applications cannot be accelerated, such as SHTTP, streaming media, or file transfers. The compression of certain files such as pictures can have a negative effect on the browsing experience of the user, due to the lower quality that it imposes." (Wikipedia)

Sources & Additional Information:
Wikipedia