Thanks for the site links 40hz.
I don't know anybody that actually needs 64-bit Windows.
Perhaps I don't need it but I won't know until I experiment. I'm locked into Windows for reasons that don't matter here. I've always found that more RAM speeds up and simplifies a lot of stuff and 64-bit systems seem to be the gateway to more RAM.
What are you going to use it for if you don't mind my asking?
If I'm working I'll typically have a bunch of hefty files open in CS3, flipping them between Photoshop, Illustrator, InDesign and Acrobat, as well as several MS-Office components and WordPerfect (both GUI and [gasp!] DOS versions, and some custom-written stuff that has to run (or think it's running) under DOS. Plus I'll be downloading and looking at some T.V. spots. And there's a whole bunch of other stuff going on. I want as much as possible to stop the machine from touching the disks, which is annoying. Generally speaking I try to keep one HDD for the O/S, another for program files, one for data, and one for downloading.
The system will replicate what I have now except that, since I'm forced to create a replacement, it'll have a somewhat faster CPU and, also, I'm trying to get the damned thing to be as quiet as possible. My days of being on the bleeding edge are over, I stay behind the curve; that being so, it doesn't take long to lose touch with what's hot. Up until the machine that I'm about to replace I've had all-SCSI systems which I've found rather more solid when it comes to multi-tasking, and when adding hardware devices.