The DRM isn't really what bothers me...my biggest gripe is that Microsoft, (admittedly, IMO) borked the audio in DirectX 10 by favoring stability over quality when it comes to 3D positional audio. I think removing DirectSound3D was a mistake, although time will tell. Hopefully, OpenAL will solve all of that and vendors will move to hardware-accelerate OpenAL, but current EAX games are a wash, unless you have a Creative card supported by Alchemy (still a work in progress).
I also hated UAC while I was testing the RC's of Vista, enough that I laughed at the Apple "Cancel or Allow" commercial. When I disabled it, I got repeated annoying prompts that I wasn't safe, and I also had a program or two that Windows didn't trust at startup no matter what --I had to tell it to allow it every time (there was no "Allow this program to run from now on, since I trust it" check box).
On the plus side, I liked being able to easily redirect all the "My ..." folders, and Internet Explorer rendered pages extremely fast. Still, other performance aspects weren't good enough for me to switch. I have a faster system now, so I'm tempted to try it, but I'd be ticked at losing positional audio in a bunch of my games, so that kills it. Perhaps when I look at buying a new laptop, I'll go Vista that way, since I could go back to XP later.
Intel Q9450 @3.2GHz, Gigabyte GA EP45-UD3P, 4 x 2GB G.Skill @4-4-4-12
Antec P160SW case (modded), Xigmatek 750w PSU
3x 500GB (RAID-5), , OptiArc 7200S, ASUS E818A3T
Creative X-Fi XtremeGamer, Hauppauge HVR-1800, Radeon 4890