Are you having or have had lag issues since going to vista or 7 while playing online games? I have, and here is how to fix it.
1. Open regedit
2. Go to: HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionMultimediaSystemProfile
3. Open NetworkThrollingIndex and change the value data to FFFFFFFF to disable the network throttle
4. Reboot
If you do not want to disable it but change the value, you can pick anything from 1 to 70. The default is 10.
Microsoft Support Article KB948066