One says gaming, all say gaming. 
I am playing all sorts of "high end" games on vista, namely, Doom 3, UT2005, FEAR, Far Cry CSS, and STALKER and many more. All are awesome. Nearly all games except CSS needed patches for running on vista. But after I downloaded the patches, all game were awesome.
I am on vista since long (almost 10-11 months) and I have a dual boot system where the other system is XP and I have not booted in XP for long.
So, only five primary reasons you wont love Vista.
1. If you cant download patches, you will hate vista for games. Normal reason: You cant download because you don't have a legit copy. :tongue:
2. You have RAM less than 1 GB.
3. You don't have a basic GFX card.
4. You don't know how to search for ur hardware drivers!!
5. Your favorite application is not yet compatible with Vista.
Vista I think is much much better. Reasons are so many I cant mention. But some are:
1. Much more secure. PROVEN.
2. Speed of booting up and down.
3. Interface.
4. Ease of use and attention to detail. Eg. anyone remembers how many settings it took for a simple headphone to a speaker shift took in XP if you have two audio setups?
5. Less clutter.
Dont want to offend anybody and neither want any flame wars but in my opinion Vista is the best OS from M$. I still dont compare it with any Linux or Mac distro but definitely the best Windows.

I am playing all sorts of "high end" games on vista, namely, Doom 3, UT2005, FEAR, Far Cry CSS, and STALKER and many more. All are awesome. Nearly all games except CSS needed patches for running on vista. But after I downloaded the patches, all game were awesome.
I am on vista since long (almost 10-11 months) and I have a dual boot system where the other system is XP and I have not booted in XP for long.
So, only five primary reasons you wont love Vista.
1. If you cant download patches, you will hate vista for games. Normal reason: You cant download because you don't have a legit copy. :tongue:
2. You have RAM less than 1 GB.
3. You don't have a basic GFX card.
4. You don't know how to search for ur hardware drivers!!
5. Your favorite application is not yet compatible with Vista.
Vista I think is much much better. Reasons are so many I cant mention. But some are:
1. Much more secure. PROVEN.
2. Speed of booting up and down.
3. Interface.
4. Ease of use and attention to detail. Eg. anyone remembers how many settings it took for a simple headphone to a speaker shift took in XP if you have two audio setups?
5. Less clutter.
Dont want to offend anybody and neither want any flame wars but in my opinion Vista is the best OS from M$. I still dont compare it with any Linux or Mac distro but definitely the best Windows.