Alright, I have a Dell Dimension 8400 (junky I know) well I recently acquired a Nvidia 6800GT from a friend to put into my computer to replace my ATI X300. When I booted up for the first time I got lines in my screen and I thought it was just a driver problem, so I installed the new drivers and nothing improved. So then I ran a driver clear program to get rid of any old existing drivers from ATI so I would not have a conflict. I inserted the 6800GT back into my computer and booted up and I had lines, but no drivers so I continued on to install drivers and everything got worse, I could no longer see the welcome/log on screen on XP for it was a bunch of lines. Everything is connected properly and I or any friends can not seem to figure out what is wrong. Also with the drivers installed my computer gets really slow and doesn't process hardly anything. I have tried drivers from two different places and I have no idea what the problem is can anyone offer some help please.