How many programs do you have running in the background?
Press ctrl/alt/del - click on "task manager" and shut off anything but critical windows programs, your anti-virus program, and your firewall. It would probably be a good idea to create a second account for yourself just for gaming that has no unnecessary programs starting up and is a user account - not an administrator.
How much ram and what size processor do you have?
If you think you were infected at one time it might be a good idea to download and install Hijack This as per the directions given you in the following link, and post the log as directed.
How to get help using Hijack This and get a team memberís assistance:http://www.bleepingcomputer.com/forums/How...s_Log-t956.html