When you installed the DirecPC, DirecWay, Earthlink or Pegasus software on your computer, it installs a registry key called GlobalMaxTcpWindowSize. If you are using WIN2K you should upgrade to Service Pack 2 to fix a bug in this key that causes DrTcp changes to have no effect on RWIN. If you don't want to upgrade to SP2, then you must delete the key. Note: You do not need to delete this key if you are using Win2K SP2 or above or XP.
Using Regedit you can find the key at: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Open the Parameters folder and locate the key GlobalMaxTCPWindowSize, right click on it and choose delete.
After the key is deleted you can set your RWIN with DrTCP, reboot, and the RWIN you selected will be used.
Remember, that if you upgrade or re-install your satellite software, you will need to use regedit to delete this key again.