I've loaded it onto this machine and one other at my house. So far, so good. My only complaint was that it turns on XP's internet connection firewall. My Linux firewall is sufficient (and better), so I turned that back off. (It doesn't ask.) That's apparently caused a number of people trouble with file sharing. I've been reading the horror stories as well, so all is not necessarily well. I've yet to risk it on my work laptop. I'll let it stew here a home for a couple months first. I did the same thing with Service Pack 1. It caused a lot of people problems, too.
If you install it and it does cause problems, you should be able to back it out. It saves all the files it replaces and you can uninstall the service pack to get back. Supposedly anyway. I know it saves the files, but I can't vouch for the going back part. Never had to.
