I don't know if you are able to lock services. There are an abundance of options in XP professional within gpedit.msc that may allow something close to what you need to do.
A third party utility that is extremely good and alerts you of any attempted changes within Windows is winpatrol by BillP Studios (freeware).
This adds an extra layer of security and lets you take full control with what happens to your operating system.
You can read all about it on their homepage:http://www.winpatrol.com/
I have been using it for years and am very happy with it.