Thats right, after years of denial, Microsoft finally decided to come clean, and has stated that Windows XP talks to the mother ship every single time it boots up! Scary! Angry? If you have Service Pack 2, and who doesn't, your Windows XP software is sending personal identifiable information back home to Redmond. Take a look at this page directly from Microsoft!
Read the entry stating "What information is collected from my computer?" near the bottom.
http://www.microsoft.com/genuine/downloads/FAQ.aspx?displaylang=en