I have built my last few PCs, and I've been happy with how it worked. I may never build another though; all but one of the household machines are Macs now. Still, it's good to get a quick summary of the current state of the art. I'm surprised to learn that the 10K rpm Raptor boot drive made such a big difference, but I'll buy it. For what I do the onboard video, however, is not really an issue. It would be different if PCs, for example, made use of the video card for RAW image rendering (maybe under Vista?).
PS. I like Coding Horror, but he really doesn't know much about OS X or Macs. Contrary to his recurrent postings, for an expert user OS X is a much better computing experience than XP. I think it's a better experience for the novice user too, but both OS X and Vista are lousy options for novices. For the novice OS X wins primarily because of Apple's hardware and the absence of the antiviral software hassle, not because it's enormously better than XP. No comments on Vista, I've not used it.
Update 7/24/07: CH has a cumulative summary and a set of suggested configurations.