How To Test DX9 Video Card?

I would like to know please what the *definitive* test is for testing a DX9 video card?

I am having ongoing problems with the mmorpg LOTRO where I get:

1. Crash to Vista desktop in LOTRO
2. Vista reports video hardware error - typically this is where I'm running LOTRO where the VPU will restart without a stop error
3. Vista reports a stop error in the video driver - infinite loop - where Im running LOTRO and it blue sceens

I run 3dmark06, no problems. The support people for LOTRO basically said that I have done tests with 3dmark06, that "Although 3dmark is not causing any errors, your error appears to be with the GPU or with your video ram. 3dmark does not utilize all the features that your graphics card takes advantage of, and it seems like one process is causing a hang either due to improper data handling (bad ram sending bad information to the gpu) or gpu corruption (the gpu is getting correct data, but cannot process it properly)."

I have also tried running Atitool beta on Vista, and when I scan for artifacts it does not find any. When I go abort and show the 3d box, all is fine too.

I dont have the money to blow on guesses and I need to know for sure its a hardware problem and not something else. The problem is even worse as Im on AGP and that kinda puts me in a spot of needing a whole new PC.....How do I test my graphics card to be sure?

Thats not an option. Besides, I want to eliminate LOTRO from the test process.

I am interested in how to defintievly test a DX9 graphics card.

Thanks, Ive done that as per my original post. No errors under Atitool for an hour plus of artifact testing.