Windows XP SP3
Upgraded my sole Windows PC from XP SP2 to XP SP3 tonight. It seems stable so far, but then I've probably already got most of the patches that they rolled into Service Pack 3 anyway. If I hit any odd issues (other than the annoyance of it reverting my hacked uxtheme.dll so I lose my Royale Remixed theme), I'll post about it here.