I own an IT company and have been using Vista Ultimate, Business and Home Premium on the 5 computers that I own, 3 laptops and 2 desktops without any issues. In our office we have been using Vista business for about 6 months and it's rock solid.
The only issues we have run into has been legacy programs which are all but history in this day and age, not that we haven't had to figure out our fair share of issues with our many clients but in the end it all worked out.
Vista in my opinion was probaby the most stable Windows release ever.
The media center option looks amazing aside from some small refinments to the functionality it's very nice. Almost 3 years ago I set up my 05MCE box and had similar challenges and eventually it all worked out and I am acutally selling it to a client minus the many tuners of course.
So yes I say I am Graduating to Vista Ultimate X64 ;)
Vista Ultimate Intel Q6600
2 Hauppage MCE 500 1 Pnnacle 800e
4096MB Ram
(4)750GB Raid 5 (2)500GB SATAII
XFX 8800GTS 640MB
2.0Tb Video Storage 500GB OS 500GB Misc.
Sony Dual Layer +/-DVDRW
C. Master Cosmos Case
Zalman 850W PS