Well I typed this responding in another thread but I'm to lazy to retype it with minor changes so I'll just copy and paste it.
Edit: Sorry if there was some confusion but this is comparing XP and Vista, not Mac. There should be no further discussion of OS X, Linux, or any other OS in this thread, if you want to discuss that go to the thread about it.
Don't think I'm just some Mac fanboy that is just hates the OS for no reason. So lets just sit Mac aside and compare Vista to XP. What useful features does Vista have over XP besides the appearance? Very few. I don't know that I would even say the appearance is an advantage since it doesn't actually do anything besides use up all of your resources and make everything else slow as ****. If you look at some benchmarks XP beats Vista's ass. Vista has widgets (which Mac has had for a while) but I find the setup annoying, and there are very few quality ones. The other day I had trouble finding a good calculator widget (which is default in Mac) which is very basic. Vista has the indexing search (which once again Mac already has), but thats not too amazing. I would love to upgrade my Windows partition to a better version of Windows but since Vista has many compatibility issues, and is inferior to XP IMO, I am unable to do so.
So just state your opinions about the two OSs.