The Windows 2000 server product is not a primary focus for development nowadays. It's probably more stable because of that. MS still issues patches and hotfixes for that OS, but they're interested to push you toward the newer version. (See Retiring Windows 2000 Server and Advanced Server [microsoft.com])
Windows 2003 is quite stable now, and that is the current recommended version. You'll be better off with the newer version in this case.