In fact, some minor instabilities I had previously experienced with some of the Office 2007 programs under XP seem to have disappeared. It's been almost two weeks, and I've had no unplanned program exits, slow-downs or other unexpected behaviour. Essentially, SP3 is a cumulative roll-up of all important updates released since XP's birth, plus a few extra hotfixes that never made it to the general population. Once installed, Windows reports itself as 'Service Pack 3. V. 3180".

If you were hoping for a raft of new features to make your machine more Vista-like, then you'll be sadly disappointed. So far, the only new inclusion that's become evident is Network Access Protection (See http://www.microsoft.com/technet/network/nap/napfaq.mspx), a technology that exists in both Vista and the upcoming Windows 2008 server.

While I'm not suggesting you start trawling your way through torrent sites looking for it, if you happen to come across a 340MB file called windowsxp-kb936929-sp3-x86-enu.exe, then it may be worth the download (or you could wait for H1 2008, when it's slated for official release).