Sure is a buncha lookin' for issues where none exist. At this point, I've deployed SP2 on a number of standalone machines and across several networks and haven't had a client bitch yet. There have been some minor issues related to security and privacy apps, but they're already well-documented and easily overcome, so far as I've noticed. Many 3rd-party vendors' websites provide updates (which, if you properly keep your product updated, or if it is set to auto-update, you've likely already got) to allow their products to mesh with SP2, or specific product configuration instructions. If in doubt, visit the product vendor's website and check ... if they have an SP2-related patch or advisory, it will be headlined on their splashpage.
Still, if you're paranoid about it,
Here's A Script that will block it from auto updating. If you are unfamiliar/uncomfortable with using tools such as this script, then you definitely
need the update anyway, so don't even bother to ask for an explanation of how this script works or how to get it to work. You can always turn off Windows Auto-Update and avoid going to the Windows Update site for a while, but that's really not a very good idea.
Oh, and BTW, the auto-update delivery of SP2 for WinXP Home machines begins tomorrow, Aug 25, so whatever you intend to do to get ready, you'd better get your butt in gear and do it.