adding a video card to a dimension e310

I know that there are quite a few threads on this subject, but I am stumped.  I added a ATI Raedeon 9000 to my system because I want to run some programs that use 3-d graphics and shading.  The install was smooth.  It was recognized and the install of the driver fine.  When I hook up my monitor to the card, I get a blank screen.  The system says there are no conflicts.  If I disable the onboard video, the screen goes blank, and I get nothing from either port.  What do I need to do to use the card for my video?  Is the problem that the card is 128-bit?  Or should I assume that the card is defective?  Has anyone had success hooking up this video card to an e310?