[new.puree]

The last time I upgraded my video card, I recall simply plugging in the new one for the old one. There were no errors or anything.
It was a nvidia card-> another nvidia card and they used the same drivers. I've ordered another nvidia card (6800gs) and will be upgrading as soon as it arrives.

Do I have to do anything else besides switch the cards? What possible problems might occur. And also I have to mention that its a agp->pcie upgrade on the same mobo(yes my mobo supports both). Is switching the main graphics interface to pcie first before installing the card necessary?

[KryptoKnight]

I know someone posted the same exact thing yesterday... look for it.

[NathanM]

Not sure about your second question, but most newer video cards use a lot of power, and thus require a direct connection to your PSU. The 6800GS will need to be connected to your PSU through a PCI-E power cable.