It is actually less compatible with some networking and other hardware. If you want to create your own Domain (login domain) for Windows XP Professional computers to log on to, then get 2003. If you want to have a large network with many computers connecting to a single computer, then get 2003. If you need to manage many users (100s or 1000s) on your network, get 2003. IF you don't need to do any of those things, then most definitely get Windows XP. It's much, much cheaper. Some editions of 2003 cost thousands. You may be better off with Linux (usually free) or eComstation (70 USD). They can do many of the things that Windows Server 2003 can do. Or if your hardware is up to it, try Vista, or try the beta version of Windows Server 2008. Both Vista and 2008 have much steeper hardware requirements than Windows XP and Server 2003 though.
