Ok i have a pentium 4 dell dimension 4600 desktop, it came with 512mb ram and a nvidia geforce fx 5200 graphics card. I recently got 1 gb of ram put that in my computer everything was fine then i got the new XFX geforce 7800graphics card and put it in the agp slot and it fit in fine then i connected it to the power supply through these wires that were also connected to the power supply and then i screwed the card in and put the side of the tower back on. so i reconnected everyhting and when i booted up my computer it showed that the monitor was on but nothing appeared on the screen and it just stays black. so then i put my old card back and it worked fine and when i put the driver disc for the new video card a message pops up and says go to www.nvidia.com and download the VGA driver and i dont know what that is. so can someone please tell me what to do so i can fix this problem. if you need more info let me know i would really appreciate any help.