In case you haven't used it before, TotalIdea has a version of Tweak-XP for the 2003/.NET server. The trial version has (I think) a 50 execution limit, but it only takes a few times through it to tweak all the settings to your liking. There's some good Cache/Memory/Hardware and Network optimizations in here, as well as a bevy of useful utilities fordisk cleanup, ad blocking and just about anything else.

Tweak-XP .NET