Games Lagging Then Relates To Other Problems On Computer !! HELP

When i download Counter Strike Source, i start the game up i seem to have a massive lag and my computer goes propa slow and i have checked my internet connection and that is fast and when i am playing counter strike source it shows my Ping to be at like 8 or sumit round that. I have also got a ATI Radeon 9800XT graphics card and that is also up to date with the latest drivers, when it starts to lag as well my computer will crash and i wnt be able to do anything and them my computer will turn off and i have my computer not start from when that has happened and i would have to wipe my hard drive and start all over, i have done this like 5 times. The only thing that goes wrong when i am loading everything back onto my computer is that i cant save Service Pack 1 onto my computer i would have to Open it first and do it from there, duno y it does this also! SOMEONE HELP PLS

Thx Tozza

Also when i am playing counter strike source my computer starts to make a funny noice and the small red lights to say its doin things that comes on and doesnt go off then i get a crash. HELP

Thx Tozza

Sz not Geforce dont ask why i wrote that, just ATI Radeon 9800XT :D