Lastest reports reveal that the Windows 2003 Server line shows little changes over Windows 2000 Servers, other than the inclusion of IIS 6 and the XP style interface. Indeed, Eweek.com are claiming here, that the whole thing is more befitting a service pack or Second Edition release than a full, new product in its own right. Perhaps the title Windows 2000 Server Second Edition would be closer to the truth. But there are some changes:
[COLOR=royalblue]"For IIS users, the new, cheaper Web Edition of Windows Server will bring cost savings when expanding IIS Web farms, a competitive response to the low cost and maturity of Linux- and BSD-based Web servers. IIS adds a number of Unix-style playing cards to its hand in this release, including text-file-based configuration, much tighter security defaults, user-level instead of administrator-level privileges, and a kernel-mode HTTP request handler and cache."[/COLOR]
More here. In fact, if you are that interested, there's a whole lot here.