Thank you all for all your most helpful input. The system got built and works fine, except one of the fans that came with the case is kaput. Oh, well, I'll replace it with one of those glowy LED fans.
One little warning in case anyone is interested- if you build a Win XPsystem with a zip drive in it, leave it unconnected to the mobo until AFTER Windows XP is installed. Otherwise, it will wreak minor havoc by assigning your (main) hard drive some other letter besides C: (in my case, I got E:) and any subsequent programs that look for drive C: as the hard drive will not find it and lots of software may not work or even get installed (properly).
I had to disconnect the zip drive and reinstall XP (that's really not too bad, as far as problems go, but it's still annoying) to set things right.
And- Microsoft's website is of little help in this matter. They acknowledge the problem, but no solution.