I wouldn't judge Vista in it's current state since most of the driver supports are not even there yet. 90% of the drivers are still beta. I am running Vista on my computer in a dual boot setup and i have no problem with it. If it acts up on me i just boot into XP. I am not sure why people complaining so much about that and comparing Vista to XP. XP is out for about 5 years now and it was a pile of shit when it first came out too. I would give Vista few months until driver support catches up and then it will be ok. I dont think there is any killer app. that runs on only Vista that forces you to get Vista right now. Wait a few months and it will all be better.
If you run XP64 you should know that already. I had XP64 and nothing was working with it, so i got rid of it. I guess it is better nowadays, but i would still prefer Vista over XP because of the DX10. All the DX10 games got pushed back to Q3 and Q4 of 2007 so that gives some time to Nvidia, Creative and all the other companies to catch up with driver support.