A little late on this one, but Dana points to an op-ed by Bruce Schneier. As Dana said, “when Bruce speaks, most people listen.” (And for good reason - he happens to be the author of a few must-read security books, among other things).
I think this sums it up nicely:
SP2 is an important security upgrade to Windows XP, and I hope it is widely installed among licensed XP users. I also hope it is quickly pirated, so unlicensed XP users also can install it. For me to remain secure on the Internet, I need everyone to become more secure. And the more people who install SP2, the more we all benefit.
Amen to that.