I built a computer back in Feburary of 08. I am currently using xp as my os. Heres the problem, I built the computer for gaming purposes. Here are the specs.

Intel Core 2 duo e6750 2.66ghz

gigabyte ga-p35-ds3l motherboard

x2 1gb sticks of ram (my mobo has 4 slots. I also plan to uprgrade to more)

radeon 3850 512mb video card

300gb western digital hdd

650 watt power supply

2 dvd rom drives

I currently have the computer hooked up to a 19 inch widescreen tv. I have a gamepad (saitek cyborg rumpble) and I played many games with this set up. I want to upgrade to dx10 and buy some newer games like assasin's creed so i can have a "vista gaming experience." I have no plans to make any drastic changes for a while (like change the mobo per say).

So heres the question.

what vista is the best for me. I don't really know if ultimate's features will have use for me. I have an old laptop that works for my ms office and internet needs. Also would 64bit work for me, I mean, the gamepad has 64bit drivers, and i don't need to worry about program compatibilty too much.

That much said

ultimate or home premium? (or basic)?

32bit or 64 bit?

Vista Home Basic does not include the Transparent windows/flip screen, contains less games and no media center. If you just want Vista to it's bare bones then Basic will save you money. I have Home premium on my laptop and to be honest I don't even use any of these fancy features, but each to their own I suppose.
You appear to be upgrading for the newer DX10 features, but in my opinion it's mostly hype. I mean the differences are pretty subtle, even in games that make better use of these new features like Crysis.
I've used Vista on various Configurations and to be honest XP is faster with quicker response times hence why I use XP on my desktop machines. Is it worth bogging down your nice machine with bloat?

Fact: Early performance issues were due to poorly optimized drivers.

ExtremeTech shows no difference between the two:
http://www.extremetech.com/article [...] 495,00.asp

Regarding versions: Skip basic. Your machine is more than good enough to go whole hog. Now - If you use your own media apps, I would actually recommend getting the Business version. MediaCenter is pretty decent. But a lot of people replace it anyhow with the app of their choice. If you're one of those, then the Business edition will get you Remote Desktop, complete backup and restore, and some decent management utilities.

Anyways, forum trolls notwithstanding: If you want to use Vista, then use Vista. If you don't then don't.

Home premium should be plenty. Business is nice, I've used that as well, just no media center or anything of that sort. But still all the aero features and what not.

This article has a chart that will let you look over the different features in each package and also talks about the 32bit or 64bit options:
http://techreport.com/articles.x/15009/10

imho, all you really need is home premium...

Like the others said, Home Premium would be great for you in my opinion.
And what Scotteq said is right.

In my experience, my pc actually blazes through anything and everything much faster than in xp, your ram is used to a much greater (and therefore better) degree, i use to lag like hell in supreme commander in xp, in vista, my settings are higher and i havent skiped a screen yet (tested with much more hours of gameplay, and maxed pop limit of 500 ).
DX10 might just be a hype for some things, but its not like xp will get dx11 or anything else ever

Oh, and definitly get 64 bit, why not be set for the present and near future