Computer lag

Some more info might be helpful...........like what good components are we talking about ? When does if lag ect.

watching videos playing games like starcraft 2 and world of warcraft
i bought it from one of those overpriced pre built computer websites.
nvidia 8800gt
amd turion 3.1 dual core
700 watt power supply
good case and a decent hard drive
i just upgraded the case originally i thought it was heat because my computer was always overheating but

now my temps are fine and it still lags

Turion is a laptop processor right? Also how much memory do you have ? Windows 7 x64 likes having 4GB of RAM to run smoothly.
How full is your hard drive and have you defragged it recently?

The Turion and 8800GT are getting a bit old but should still be decent although I am not sure how well they would do with Windows 7 x64.

sorry i meant Athlon 64. and i have 4gb of ram

This is a duplicate thread. The other one is at http://www.tomshardware.com/forum/291286-31-help