Personally, I love XP. I think it has matured into a very stable OS, but has had its growing pains just like Vista is having now.
At this point, I am actually glad to see Microsoft stopping sales of XP and kind of disappointed that larger companies like Dell are still selling computers with XP on them. The only way Vista will mature is for people to use it. It isn't nearly as bad as it was when it was released, and right now I would have no problem running it on all my machines if I could afford licenses for all of them.
Rig1: System Specs.
Rig2: A8-5600K@4.4GHz / AsRock FM2A75 Pro4 / 8GB Corsair DDR3-1600 9-9-9-24 / HD7560D / Samsung DVD-Burner / 1.5TB WD Green + 3x3TB WD RED in RAID5
Rig3: Athlon X2 4200+ / M4A79 Deluxe / 4GB G.Skill Pi DDR2-800 4-4-4-12 / GT430 / Sony DVD-Burner / 500GB WD
Rig4: Phenom II x6 1605T @ 3.6GHz / Asus M5A99X Evo / 8GB PNY DDR3-1600 9-9-9 / GTX470 & GTX470 / Samsung DVD-Burner / 1.5TB Seagate