I'm sure everyone is sick of these, but would it be worth it to upgrade from a Radeon 9800 Pro 256 to a nVidia 6800 GT 256, or should I just wait until next fall to build a new system?
I to say wait. Its not the video card, any PCI-E card will last a long time as PCI-E is new and has awsome bandwith. Its not goin anywhere. Chances are your cpu wont be able to keep up with a 6800 anyway. Wait a few months when socket M2 comes out for AMD (asuming you want AMD) the M2 will support DDR2. Vers F will be the way to go and it is said that this new M2 will "pave the way for the quad-core processors AMD expects to ship in 2007, but they will also be used by single- and dual-core chips too." If this is true then predictions are right the era of speed is over. It will be about more cores working more effeciantly together offering much better performance overall.