HIS HD 2600XT 512MB Card not working properly

I have been having trouble with my computer either not posting with HIS ICE Q Turbo HD 2600XT 512mb vid card installed or if it does boot to os it locks up after sometime or right away at login screen. I was thinking it was a Powersupply problem since I had originally a Antec Model# SU-430 so I took the card to work and it worked fine on a different system with a enermax FMAII 460w powersupply. So I went and bought me a Anec earthwatt 500watt powersupply with the same 12v1 22a and 12v2 20a voltages as the Enermax PS but it at first posted and booted I installed the drivers went to restart then the system did not restart. I turned it off then it booted fine then locked up in the os. Then I returned the Antec earthwatt and got on advice from bestbuy techs the BFG Tech 550W GS series Powersupply this does not have same ampage from the rails 12v1 18a 12v2 18a, It then posted adn booted worked fine until I tried to play a video game then it froze rebooted tried again froze rebooted now it is now back to not starting up at all. I can put in the my old Video Card a Geforce 7300LE and it posts and boots no problems plays games fine. So my question is what Powersupply will make this card work or are the 2 Powersupplies I have selected fine for what it needs or is my motherboard (Asus P5VD2-VM-SE) having problems maintaining the power for the card slot? What do I need to get this card to work with my system? I have already RMA it (newegg.com) thinking it was the card so I got a different card now I cannot get a refund so I am stuck with it.

CPU: 3 Ghz P4 with Hyperthreading
MB: ASUS P5VD2-VM SE
Mem: 2gigs DDR2 667
1x IDE Hard drive
1x IDE DVD drive