I’ve been a pretty big fan of Vista so far at home. This week I installed Vista on a machine at work. While the machine is a slightly older one, its no slouch – its a 2.66GHz Hyperthreaded P4 with 3GB of RAM. But the machine is as slow as a dog running Vista. I had no trouble with XP on this system, but Vista is janky; it frequently lags and stalls doing basic operations.
If upgrading to Vista, make sure you’ve got a dual core system. I’d bet that the vast majority of developers at Microsoft run exclusively on dual core (or better) machines. [We developers at Google probably do too, but at least I’m still using this one :-)]