From a purely practical standpoint, since you have a powerful rig as it is, I would not move on to a new rig until you are ready to move on to PCIe. I would imagine there will be more highend cards being offered in the PCIe format than AGP.
That being said, if you are a hobbiest, and change your rig alot, go for it, test the waters, and decide if you like it. I'm a recent convert to A64 754 from a highly oc'ed P4. There are differences, but nothing monumental.
That being said, if you are a hobbiest, and change your rig alot, go for it, test the waters, and decide if you like it. I'm a recent convert to A64 754 from a highly oc'ed P4. There are differences, but nothing monumental.