AIW7500 cannot POST, any suggestion?

[Dartsen]

Just got an AIW 7500 to replace my Voodoo 3 2000. I first uninstalled the 3dfx utilities, and then deleted the Voodoo 3 adaptor in Device Manager. Then I shutdown, change to 7500, and restart. System (Win 98) boot up no problem with default VGA adapter driver. I have downloaded the new ATI drivers (Catalyst 2.5). However, the manual suggests to use the original CD for install, and update drivers if there is a problem. I then run express install from the ATI driver CD. Though driver installation failed, the progam went on installing other stuff (media theater etc), till the system froze with fatal error showing. The supprising thing is that I got a black screen after reboot, even with the original Voodoo card. I checked the voodoo card on my other system (using matrox G-200). It is perfectly fine. Does anybody have experience about what is going on? I am using an Athlon 900 on a microATX board (forget the model), 250 w PS. Any suggestion will be appreciated.