I prefer Coke myself... It's not as harsh on the palate.
Back on topic....
I was a user of Tune-up Utilities back in my XP days, and used it a bit when I ugraded to Vista. While it seemed to do OK with XP, I can attribute the registry cleaner aspect of the program to at least 2 reinstalls of Windows Vista.
I haven't looked back since. When I feel the OS is getting to the point of no return with too many program uninstalls, I load a vanilla image of my install. Everything is as good as new in 10 minutes.