Well, Server 2k3 is terribly expensive to start. It's a Server OS, so it's built on stability, not functionality. It's not fully supported yet, so you're going to have driver problems, and possibly hardware problems (make sure to check the HCL for it before installing it. It pro'lly won't work too well on legacy hardware).
If I had to choose between the two for a workstation, I think I'd rather poke myself in the eye w/ a pointy stick.
There's no real benefit to warrant installing Win2k3 Server on a home PC unless you're an enthusiast who likes doing things the hard way.