Not being pingable is as a result of your firewall - router or software firewall (Windows has one built in). For your router you'll need to log in and go to security and check something like:
respond to ICMP (Ping)
or something like that. Similar in your Windows Firewall as well.
For your speed issues - what are your network signal levels? To find that out you'd go to: »
192.168.100.1 and then post that info here.