vista or xp

everyone talk about vista. I could not resist the temptation and end up using vista because the colour is much better. What is the side effect. Computer get very slow.Need to use the office 07. What is worse about office 07 is even the saving feature is hidden . No more save button outside. This is same as explorer. I still prefer firefox and my old office application. another irritating thing is every installation the window will ask for permission such as registry going to be changed . Are you agreed or not. To the dummies, it is confusing. To me ,it is irritating.
Maybe after certain period i will like it. If over the period of trial, i still not like it then i will need to reformat my computer and back to square one(my XP).

ps: reformat computer minimum a year once