3-3.5 GHz chips will most likely be realized on a 478 pin platform. If we are lucky, maybe even up to 4 GHz (theoretical max for P4). As the 3 Ghz chips come out though, intel will likely start phasing in their new chipsets (early next year), which will support a more numerous pin configuration and perhaps the then 'classic' 478.
New stuff is gonna be mainstream by summer next year, so you kind of have to bite the bullet now, unless you want to wait and pay top dollar when they arrive. I splurged now, figuring that by this time next year, the new stuff will be as cheap as last years new stuff is now.
as i see it too, memory is playing catch up to cpu. if you can get a DDR400 system to feed a P4, you'll be pretty zippy in the time to come.
didn't realize, you had RDRAM going... Why the rush to build a system? You got the goods to take you into the next generation!