Problems running PC game with bootcamp, graphics card problem?

Question

I have searched extensively on answers to this question and I've gotten some vague ideas of what to do, but not a direct answer.
I recently installed a copy of Windows on my 15in Macbook Pro (the ones that came out right before the latest ones in late August/Early October 2008 or whatever). I did this in order to play Final Fantasy XI Online on my laptop. The machine is more than capable of running the game and I've read forum posts that had said that it works fine through bootcamp. I installed the game and was playing it just fine until one day the game began to lag really bad in areas where there were a lot of people or in other words something very demanding of the memory/graphics. I don't mean internet speed lag, I mean the computer would slow the game down to a crawl and the sound would be sort of garbled like it was some sort of feedback. It would happen periodically or if some sort of animation would start (spellcasting, etc)
I've tried everything from changing the settings of the game so that it's not as demanding to installing modified drivers for the graphics card (256mb Nvidia GeForce 8600M GT). I read that there may be some problems with the graphics and sound cards communicating which causes lag?
The computer also gets unnaturally hot while I run the game/windows in general. Could it be a cooling problem?
Please help!

Answer 1

Processor:     
Intel(R) Celeron(R) CPU E1400 @ 2,00GHz (2 CPUs)
Memory:    
4gig,Corsair TwinX XMS2 DDR2 800Mhz
Hard Drive:    
Seagate 1 TB
Video Card:    
ATI Radeon HD 3850 X2
Monitor:    
EIZO monitor
Sound Card:    
Realtek 7.1 HD Sound
Speakers/Headphones:    
Mikomi 5.1 HD @ Headphones
Keyboard:    
Logitech Gaming Keyboard
Mouse:    
Logitech MX510 Gaming Mouse
Mouse Surface:    
Belkin Mouse Mat
Operating System:    
Windows XP Professional (5.1, Build 2600) Service Pack 3 (2600.xpsp_sp3_gdr.090804-1435)
Motherboard:    
MSI P35 Neo 2
Computer Case:    
CiT 1004 CSCIT1004 Black Screwless Gaming Case
PSU:600 Watt GreatPower
this is my gaming rig