Hp a 1726x graphics upgrade

Hello,

Just wanted to upgrade from an EVGA 7200 GS 512mb to new ON-XFX1-PL 1gb graphics card, but when I turn on the PC I just get fan sounds and no display. I did in-install the old card and its drivers first and made sure the bios showed pci-e as the choice.

I know it's older, but all vendors assured me that 2.0 and 2.1 cards a backward compatible with 1.0. I am thinking this may not be the case. Any advice?

Thanks...

motherboard: asus p5lp-le
550w psu
win vista 32bit
3gb ram
pentium d
hp a1726x
bios version 5.03