I am using Fedora 16 with KDE on a Dell Dimension 4600. A couple of weeks ago I borrowed a GeForce 7600GS Video card to try see if I could use dual monitors. After installing the card everything just worked, Fedora detected all the correct settings and I didn't have to tweak a thing.
However, i had to return the card to its rightful owner and install my own card. In this case a Gigabyte Geforce 6600GT. This time I DID have to do a bit of tweaking as Fedora got the monitors the wrong way round. It made the small (1024 x 768) VGA monitor the primary monitor and the big (1280 x 1024) DVI monitor the secondary. That was fairly easily solved but the settings are not saved when I switch off. Every time I reboot it reverts back to before.
I am especially puzzled as the previous card just worked?