The number and the fact that 2003 sucks slightly less than 2000.
In all seriousness, that’s quite an answer you’re looking for. But you should really try searching on Google first. For example, I found this site with a casual (and badly-constructed, I admit) search on the Goog:
One thing I really liked, especially for enterprise-class installations, is the fact that when you reboot the server, you *must* enter a reason. This is great for audit/tracking purposes.