Leadtek 7600 GT AGP Vista drivers

So I've got a Leaktek 7600 GT AGP video card running in my machine which I recently upgraded to Vista. I'm having problems with the drivers for it though as if I use the standard vista non-updated drivers it works ok but as soon as I use new Nvidia drivers, Leaktek drivers or update the vista drivers for it I start to get errors. Things like when the little vista popup box appears when you need admin rights to do something, the screen goes all liney and it's difficult to even see the box. Once you've click on 'yes' or 'no' in the box though it goes back to the desktop and the graphics errors are gone. It's really weird. Can anyone help me out? I'll try to get a screen shot of it at some point to show you all. Has anyone had anything like this happen before?