my computer costed 1000 dollars and its the best at bestbuy and i went to a nerds club they fix computers and they couldnt even fix it
Because the "geek squad" doesn't know jack stuff about computers. I'd rather go through the pain of fixing it myself rather than let those rednecks handle my precious.
You need one source game, I think Portal will do fine.
Downgrading to XP doesn't change anything. Assuming you have Vista Service Pack 2, Vista is actually just as efficient as XP. You're really doing nothing but wasting time and clearing your hard drive off.