MBP Heat issues

So I've had my MBP for about a year and it great, but lately I've been noticing performance decreases, mainly when playing graphic intensive games. These games ran smoothly when I first got the computer but now they are quite jumpy. At first I thought it was programs running in the background, but I checked and nothing that is not system critical is running. I believe the culprit is dust in the computer. My desk at school is always dusty especially behind my computer. The only way to know for sure would be to open the computer up, which would void my 3 year warranty (2 years now). Do you think it is possible to coerce the employees at the apple store into "checking my computer" and cleaning out all of the dust?
BTW I am playing COD4, CSS, biochock, etc.

Get Onyx and do some cleaning/repair/maintenance.

already done, btw this is on windows xp via bootcamp

Try resetting the following:

1. PRAM: http://docs.info.apple.com/article.html?artnum=2238

2. SMC: http://docs.info.apple.com/article.html?artnum=303319

Both should help.