I say just buy a new system once the next gen, ie Geforce 6800 and R420 come out because in a year or two the new BTX form factor will be released and it wont matter if you got PCI express or not because it will be time to upgrade not only your videocard but you case, mobo, processor and all the rest! This is a crappy time for computer users because we need new cases that allow for better cooling (ATX) and new graphics cards for Doom 3 and the like but at the same time the next generation of basic computer parts, ie mobo are just around the corner. If you buy now you get the next two years worth out of your machine and then when you need to upgrade all the new tech will be out. Otherwise you are going to get stuck half way into the new upgrade cycle. Just my take