One possible cause is your firewall. I had problems getting SP2 and updates from the new Microsoft Update site two weeks ago. I eventually traced it to a rule I had set up in ZAPro to prevent Generic Host Processes keeping port 1025 open. I removed the "blockall" rule and was able to update to SP2 and other updates without any problems. I have had no issues with SP2 yet and even though I have not reinstated the firewall rule, port 1025 is now closed.
Although according to some answers here it may be a server problem. I have just tried Windows Update and it worked fine.
http://communities2.microsoft.com/co...xp=&sloc=en-us