''The extent is huge''?
killed all unnecessary background/startup progs.
1. "System Services for the Windows Server 2003 Family and Windows XP Operating Systems." Read the topic "Workstations" specifically, and if it is not needed, then disable.
2. "Black Viper's Windows XP Services Configurations."
3. "Windows XP Tweaking Guide - VIA/Arena."
4. Please note, that if a service runs for catalog indexing such as Cidaemon.exe that is discussed in the Win2k article [Q156756], further discussed in [Q308202] for both Win2k and WinXP, it is suggested that some testing be conducted to perhaps check whether certain services are necessary and used -- after reading the article, "HOW TO: Use Computer Management in Windows XP (Q308423)."
5. Remember Find Fast which everybody has been turning off because it's simply a system drain? Indexing for Windows XP is about the same and can be turned off. The Indexing service however speeds up and improves file searches by maintaining an index of the files that are on the hard drive but can be safely deleted.