Got Vista, and wouldn't you know it, got problems.
I'm just one of many, I know, but I might as well share with the world MY experience on Vista..
1) Initial install failed utterly. Vista told me it couldn't find a suitable partition. 'scuse me? I had just wiped 200gb on my XP drive, leaving XP on the first 120gb, and the rest of the drive clear. I ended up going back to XP, setting the second partition active, going back to Vista setup, and it let me install. Then it gave me "Error loading OS".. so it didn't like having partition #2 as active... I manage to get in with a bootable CD I'd made years ago, and run FDISK to make partion #1 active. Try to repair the Vista install, no dice. XP is safe, thankfully... So I go back in and do a second Vista install. It works this time. Go figure.
2) No audio until I did a Windows Update. Windows Update provided several updated drivers for the nforce4 chipset that I use, including an audio driver. Soon after, I blue-screen. Not a blue-screen with white text on it, but just a plain, blank as day, blue-screen. Reboot, and Vista informs me that the error was due to "NVIDIA nForce Audio Driver (nvmcp.sys)", and then tells me to visit Microsoft Update for an updated version that it assures me actually fixes the problem.... Except that I got my audio driver FROM windows update. So there isn't a newer one there.
3) Audio Part 2. I realize that of my 5 speakers, the driver from windows udpate is only using 2 of them. There's no option (that I can find) to enable the remaining part of my 5.1 speaker set. So, thinking brilliantly, I decide to download and install the Realtek ALC850 sound drivers - which is what nvidia actually uses on my motherboard for sound. They install, and I get an error on reboot that says "Windows Vista does not support Realtek HD Audio Sound Effect Manager"... Yet, mysteriously, sound is working. AND I can enable the remaining speakers. AND it hasn't bluescreened (see #2) since changing over. Yay.
4) User Account Control. I said I wouldnt' mind. I said I'd leave it on. I LIED. Turns out it is extraordinarily annoying. It causes my monitors to re-synch whenever the UAC dialogue comes up, slowing down a ton of things, and being very very very annoying. All the tips for making it less annoying? They require Local Security Policy editor... Which doesn't appear to be enabled on Premium Edition. So, UAC is now turned off.
Anything else, I have yet to run across....