For what it's worth, I have upgraded to Vista Premium Home edition. I can't really say I've seen much in the way of improvements in performance for SimX or FS9.
The only reason I would recomend getting it is "Familiarization". Learning how vista works and working with it.

:-/ That'sssss what thrills me :-/, I'm afraid that I will have trouble with all my softwares ,Not just Games as FSX/9 ,I mean video capture (I work sometimes capturing weadings,birthdays partys etc, In VHS or sony video 8 into DVD with menu and stuff like that) also I work In desigh making airplanes , and many many other things , like in decompile file to another formats ,XML,C++ , etc...what if I throw my money into the garbage and this VISTA made what Windows ME did once to me ? I mean I still don't know how this Vista works ,But I can still open things as DOS in xp ...
I been asking this question many times and seems like everyone is afraid to answer....