You'll find several long (100+ reply) threads on the topic, including this one, which was an official poll in February. To summarize, your performance will decrease to an extent and some hardware/software won't be compatible, but to many the new features and revised interface are worth it.
Given the several ongoing discussions I'm locking this one.
Im sure this question has been posed before. I have a very capable xp rig right now ith a 2.4 dule core, 3 gb of ram, and a 512 mb gpu. I do alot of power using and gaming. I have access to vista for cheap through my university and am wanting to upgrade. If i do, I am planing on putting 1 more gb of ram just for good measure. I was just wanting some advice if it was worth upgrading to vista.