I spent a large part of today reinstalling Windows XP on my laptop (it just didn't have enough oomph for Vista), and the quantity of updates really shocked me.
I started out with Windows XP Professional with Service Pack 2 slipstreamed. Immediately after installing, I had 89 updates. It took an hour to get and install them, but it was a relatively painless process that installed WMP 11 and IE7 in addition to several patches.
After rebooting, I reran Windows Update and there were a further 11 updates to the updates. Again, relatively quick and painless, but a bit confusing.
After rebooting again, I reran Windows Update and there was 1 update to the updates to the updates.
Grand total: 101 updates. It may not be time for SP3, but it could be considered time for a SP2 Update Rollup.
Now to reinstall my development tools...