Hello i need help about some information about hardware i have.

I got 2 small pc Shuttle XPC Cube SN95G5 (https://global.shuttle.com/news/productsSpec?productId=489) and Shuttle XPC Cube SS59G (https://global.shuttle.com/main/productsSpec?productId=75) I upgraded P4 cpu (945 one) and im looking to upgrade Graphics card. I used Creative Audigy 2 ZS on P4 machine. Other pc got AMD 3800+ cpu both have 2 GB ram but now they have 1 GB each. Gray machine (SS59G ) have Quadro FX500 gpu and other one has FX5500. So i tried to upgrade with FX5700VE i had some issues. Then i found gpu upgrade info at their website i bought ATI Radeon 9600 XT. I tried both pc and won't work just black screen, fan spinning everything working but no bios screen or something. Also i tried this GPU at Asrock P4V88 didn't work also. I'm trying to make one pc for WIN98 and other one maybe WINme or different OS. I have also 9600 Pro this worked but after i install driver got problems no idea which driver i need for this cards.