Blue screen crashes w/ visiontek ati radeon hd3650 1 gb agp

Hi folks, I'm all out of ideas on my issue here and I'm hoping anyone with more knowledge can give me some guidance.

I've recently had to purchase a new vid card for my older system which I primarily use to play a few online games (ie, EQII & EQ).
Since I've installed this card, I've had the critical stop blue screen crash anytime I'm in areas that have high particle effects or water animation. I've been able to detail it by constant tweaking of my in-game graphics settings. Even turning the graphics setting to the lowest possible, I still randomly crash in certain areas.
Everyone's first guess always questioned my psu but I think the 550W should be sufficient. Besides a driver issue, I have no idea what could be the problem, except maybe a faulty vid card? Is there something I'm missing or am I looking at a faulty hardware. I can't think of any other things to test myself.

Solutions I've tried so far:
- Reinstalling games and related software.
- Updated latest vid card and mb drivers with and w/o the catalyst software.
- Used drivercleaner before updating drivers.
- Tried using the version of video drivers that came with the supplied cd.
- Set my agp apeture size to it's max of 512MB per an ATI reps suggestion.

Some System specs:
MB = ASUS A7N8X-E Deluxe
Video Card = Visiontek ATI Radeon HD 3650 1 GB AGP
Memory = 2 x 1 GB
PSU = Antec Trupower 2.0 550W

I appreciate any thoughts in advance. I'm totally at a loss here and I'm about to break down and just get a another new vid card (maybe an nvidia) and psu.
Thanks for reading.