I was running Vista 64bit Ultimate since it's release end 2006 - january 2007 - and it NEVER crashed on me since then - it was the best Windows Version i've used since all the versions i've used beginning with Win 3.1 until end 2006 ... you only needed the right machine and components, to run it, so all 2007 hardware (Quadcore, 6GB Ram, fast 8800 card, since a while now a 9800 GTX+).
And - surely installing all announced official Windows-Updates up to Service Pack 2.
Since running Vista in 64bit mode, i never want to go back to 32bit ... that's history for me - a relict out of older PC times ...

Anyway - the only Problem with Vista was it's larger ressources hunger. So because Windows 7 for me is only a streamlined Vista with a better ressources management, i've switched over to Win 7 now, too.
Before that i've moved my first 500 GB harddrive with 6 partitions and all the files and folders and boot information (including my Vista OS on C:) over to a new 1 TB harddrive using a great software called "Acronis True Image 2010".
The backup from files to folder and even whole partitions and drives (cloning) and keeping all the boot information went fast and flawless (for example to back up the 45 GB content of my C: Vista partition with boot info took only about 15 min. to the 1T drive hooked to the USB port).
After that i only had to exchange the 500 GB and 1T drives in my PC. Starting up the PC it felt like the 1T drive was always installed and my Vista ran perfectly.

I've bought a SystemBuilder Windows 7 Ultimate 64bit Version (cheaper) and just updated my running Vista with Win 7.
After the installation everything was running fine, looked and worked like my 2 year old Vista before (i've had a lot of different applications, games, whatsoever installed) - only the Rivatuner gave me some problems (used it to control fan speed for piece and tranquillity ...). Now using MSI Afterburner Tool for fan speed control - works fine.

Vue 7.4 and Vue 7.5 , Poser 8, Carrara 6 and all other 2D and 3D programs were running right away - no new installation needed.
Except of ZBrush 3.5 and PaintShop Pro X2 Ultimate - they've asked for a new activation at start - but that was done in a minute online and working now flawless.

Otherwise - like Andrewball mentioned - in many places it's running smoother than my Vista before - with some improvements over Vista. But - overall i feel home rightaway in Windows 7, because most of the things and looks are totally familiar to me, because being an enhanced Vista for me.
For someone coming from XP or even older versions of Windows OS it for sure is a new experience - for a short while. Like i got used to Vista in 2007 real quick, everybody switching over to Win 7, should be getting used to it just on the fly ...