Big freaking problem =[ Please help Comp Freezing/Crashing

[BroodsteR]

The problem :
When I play direct x games my comp will either crash or freeze.
Games I've tested:

Warcraft III - Crashing
NBA Live 2005 - Can't even finish one damn game, freezes my whole comp, needa hit my restart button
CS:Source - Havn't experienced much problems but sometimes game won't load up.

My computer specs
Motherboard : GIGABYTE K8 Trinton Series nForce 3
CPU : Athlon AMD64 3000+ (not over clocked)
RAM : 2 512mb Kingstons @400mhz (non dual channel)
VGA : ATI Radeon 9550 Extreme (Manufacturer: Grandmars)
Soundcard : Onboard
Network : Onboard
Others: Firewire Card (recently installed, possible link to my problem)

What I've tried:
It can't be my hardware issues, because all my hardware seems fine. Well nothing started happening since I installed my Firewire card but I don't see how it can be causing the problems unless anyone can give me ideas. So I formatted my computer because i got tired of trouble shooting, and.... installed NBA Live 2005, tried to play, FREEZE, same problem =[

So now im pissed off because i spent 5 hours backing up all my data which didnt even fix the problem.

Can someone please give me some sort of idea on how to fix this?

 

[BroodsteR]

and guess what... I took the Firewirecard out, poof goes the problem played nba live 2005 for over 2 hours. No problems =D Damn u firewire!!! Why'd i buy you anyways [edit] actually im still getting the problem now. Could it be my ram? Sometimes when i start my comp it stalls before it tests my memory

 

[BroodsteR]

Could someone please help me?