PC won't boot with new 9800 pro video card

I'm installing an HIS Excalibur 9800 Pro, but after plugging in the card and the power connector, my PC won't boot up. Instead, it immediately goes to standby mode. When I reinstall my old graphics card, everything works fine. As far as I can tell, I meet the recommended system requirements.

My specs are:

Athlon XP 2400
Gigabyte GA7DX (rev. 3.0)
512 MB
Antec TruePower 330
Windows XP

Any ideas what the problem might be? Thanks in advance.

load the rad drivers remove the old graphics card from the device manager and if on board graphics disable it in the bios  and then put in the the new graphics card in a re-boot..does it solve it..