A lot of people (maybe vocal minority) having problems. Here's the weak system I run this game on -

WinXP Home 32-bit
AMD X2 4800+ 2.5 ghz
4 GB DDR2 RAM
Nvidia 9600GT 512 mb

Playing at 1280 x 1024. Game suggested medium and I turned off or down a couple of things out of habit (AA and forget what else, but can update this later). Game had a couple of hitches where it seemed to lock up for 1 second and then continued smooth as butter in the opening area. Once inside not a hitch. This game looks incredible, animations incredible, really happy and surprised at the performance.

I am currently working (but snuck in a little bit of gaming) so I haven't ventured further but just wanted to post this for people with much more powerful systems. I also have a quad core phenom 3.4 ghz with a Radeon 6850 HD and absolutely gorgeous and smooth but kinda expected on that system.

Back to work for me - but if you are having problems with your system maybe update drivers (video, audio, heck even drivers from your motherboard manufacturer). All your computer parts are related to each other and sometimes the weirdest, least paid attention to drivers (and background processes like antivirus) will make all the difference.

I don't know the percentage - but I'll bet it is pretty high for people that have problems with games nowadays that can be traced back to their own computer.

This may be my only post (due to work and I plan on living in Skyrim uninterrupted for a long time), but just wanted to give some hope to people having troubles when you see that a weak computer is running just fine.