FX5900XT-VTD128 - System keeps restarting

Question

My system keeps restarting and windows is saying it's a graphics card driver problem.
The driver I am using is v6672 from MSI LiveUpdate.
I am currently running this card on:-
AMD AthlonXP 3200+
2 x 512Mb 400Mhz DDR RAM (Dual Channel Mode)
MSI K7N2 Delta-L Motherboard
PSU - 400Watt Ebuyer Value
Sometimes I can play a game full resolution for ages and it won't crash and sometimes just 5 mins.  Also it will reboot while doing simple things.
Any help would be appreciated, thanks.

Answer 1

0 - System Timer
1 - Keyboard
3 - COM2
4 - COM1
6 - Floppy
8 - System CMOS
9 - MS ACPI-Compliant System
12 - Mouse
13 - Numeric Data Processor
14 - Prim' IDE Channel
15 - Sec' IDE Channel
16 - Creatve SB Audigy 2 ZS
16 - VIA Rev 5 or later USB Universal Host Companion Controller
17 - OHCI Compliant IEEE 1394 Host Controller
17 - VIA Rev 5 or later USB Universal Hopst Companion COntroller
18 - VIA USB Enhanced Host Controller
19 - NVIDIA GeForce FX5900XT
20 - Standard OpenHCD USB Host Controller
21 - Standard Enhanced PCI to USB Host Controller
22 - Standard OpenHCD USB Host Controller
Thats the full list, in my machine I have
AGP - FX5900XT
PCI - Soundblaster Augigy 2 ZS
PCI - Ebuyer USB 2.0 5 Port PCI card 4 external
It's strange, the lock ups just occur after a while.  I've been playing Doom 3 high resolution for ages today and nothing happened.  Yet I could go to bed tonight and wake up to a BSOD.  Then sometimes I could be doing something in Office and it will just BSOD.  I was using the PC for around 6 hours yesterday before it happened.  All graphics are fine in the games I've played, so it must be something else.
I've done MEMTEST and that was fine, and also ran CPU test and that was fine.
But...I noticed today there was something new on my motherboard that wasn't on my old.  A 4 Pin connecter and the mobo manual says it powers the CPU.  Well I've connected this up and booted the system and no BSOD so far, but will let you know if it does.