I like Sweetwater's optimization guide. Covers a lot of the bases, then kicks you over to Black Viper if that's not enough. Another op guide I saw recommended disabling ALL services....made me angry. People's computers will be unusable. There are services that are required for 7 to run. Anyway, it IS a good read.
Anyway, stick with 7 for the moment. There may be thousands out there running 8 and "getting by just fine", but 7 is stable and known. Answers are a lot easier to get when you have problems, etc. etc. etc.