I run Vista Ultimate 64bit with all 3D applications that i own (like Poser 7/6 ..4 ... - whatever version, they are all running- Vue 6 Infinite - Carrara 6 - Bryce 6 - ZBrush 3 - Hexagon 2 - OpenCanvas - Manga Studio - PaintShopProX2 - tested Cinema4D - tested Maxwell Renderer - tested Quidam - and more ...) , using test versions of 3D programs or whatever, lots of games, music programs, video programs and, and, and ... it's working great, i've got a lot more options and possibilities in Vista then i get with WinXP, with the build in stuff.
And  if someone says, they can add all and more options to WinXP like Vista has build in, you are installing a lot of potential problem causing programs and Problem is, the more foreign programs you install on your Operating System, the more crap is installed, that can mess up your OS, if it's not programmed in a clean manner, which you can't know by just installing and using it. Plus, those things could slow down your OS in certain areas, too.

I'm always installing all the available Microsoft Vista updates coming in automatically and Vista gets better and better. If you are using the newest hardware, i would recommend using Vista 64bit, since it knows a lot more about new hardware and can handle it right from the start, where XP starts to struggle slowly but surely, because of it's old base core programming and fading support in the near future.

All of the computers in our household are now Windows XP free - and they run great, even after 2 times rebuilding them from scratch, Vista worked right away as it was before the hardware change, only asking for the new mainboard chipset drivers, because each mainboard uses different chips to control the system and interfaces.
I don't miss WinXP now - i worked with it from the time, it came to the market the first time - replacing my Windows 98.

Everyone using PCs and Windows OS for a long time - do you remember the same flaming and shouting against the "new" Windows XP replacing Windows 98 and ME like now Vista trying to replace WinXP ?!  Windows XP had the same starting problems like Vista had - the bad driver and program support ! But that's changed now for Vista - there is a good driver for everything now and it's working flawless - at least for me it does.

One good hint :   if you leave the PC and hardware running as it's suppose to (stop overclocking your hardware to the edge of existence), stop installing insane software, which fiddles around in the depth of the Operating System and your hardware, because little changes could work on the one side, but cause extreme problems on something else and you don't even know, what's causing it ... Since i leave my OS and hardware running in it's regular state, i haven't had any problem anymore (i'm working with computers since 1982 - and building my own PCs since 1992 ... and i finally got sick of all the problems of overclocking and tweaking software or whatever - and now it pays off).

And now the shouters and flamers against WinXP are fighting for WinXP like maniacs now and AGAINST Vista ... it's the same story again, just a few years and a new OS later ...

Again, if you run older hardware and not enough Ram (like 2 GB is the base for Vista, better more, but the prices for Ram right now are very low ...) then run Windows XP, but if you want to use now and future hardware the right way, get a higher Vista version. For 3D programs or graphic and 3d intense programs i would recommend Vista 64bit (because it can use more than the 2,5 GB Ram barrier from 32bit OS per application) and lots of Ram (4 GB and more).