Too bad that it has to be a PC. The new MacBooks (15" and 17") would probably suit your needs perfectly. The new 17" version has been introduced only yesterday. The MacBooks even have a built-in version of Aperture (Apple's RAW processing software). And, of course, with the new Intel Core Duo processing in Photoshop becomes a speed trip. BTW, Adobe recently stated that they will support the new Core Duo with even faster applications.
Oh, I've just forgot that you need a PC. You want to run your PC software of course. Perhaps Apple's Boot Camp is the answer. I haven't tested it yet but heard good things by now. More info here: http://www.apple.com/macosx/bootcamp/
I think the Mac answer was inevitable in your thread... So here you are.