The xp-AntiSpy is a little utility that lets you disable some built-in update and authentication 'features' in WindowsXP.
For example, there's a service running in the background which is called 'Automatic Updates'. I don't know what this service transfers from my machine to other machines on the internet, especially the MS ones. So I play it safe and disable such functions. If you like, you can even disable these functions manually, by going through the System and checking or unchecking some checkboxes. This will take you approximately half an hour. But why wast time when a little neat utility can do the same in 1 minute? This utility was successfully tested by lots of users, and was found to disable all the known 'Suspicious' Functions in WindowsXP. It's customiseable, but comes up with the Default settings, which are recommended. This utility is DONATIONWARE! This means, you don't have to pay anything for this program and you can give it to anyone who's interested in it, as long as you don't sell it. If you find this tool useful, and wanna gimme something back, think about donating a small amount of money.
Thanks.

PeerGuardian 2 is Phoenix Labs’ premier IP blocker for Windows. PeerGuardian 2 integrates support for multiple lists, list editing, automatic updates, and blocking all of IPv4 (TCP, UDP, ICMP, etc), making it the safest and easiest way to protect your privacy on P2P.