I had the fortune (or misfortune depending on how you look at it) of completely rebuilding my development machine from scratch last week. The unfortunate circumstance of having a corrupted registry and destroyed network settings befell my laptop due to a bad install of a VPN client. I was able to rescue 100% of my data however, off-loading it to an external USB drive which I love. I've long been wanting to make the move to Windows Vista but for a grundle of reasons couldn't validate the time it would take to move to the new environment. Perhaps this was the kick in the pants that I needed.
Once I blew the machine away (paved it, as they say) I set forth to install Windows Vista Ultimate on my Dell Precision M90. The install went extremely smoothly - I had an operating machine in about 30-45 minutes. With the exception of the built-in laptop monitor, I was very pleased that the OS correctly identified 100% of my devices. It was peculiar that Vista insisted in setting the display rotated 90° counter-clockwise after a few reboots. Until I installed the correct drivers I couldn't shake it of this habit. Also, it's working great with my secondary Dell 2407WFP monitor
Dual 1920x1200 resolution 
I've also installed my customary applications (Office 2007, VS Team Suite 2005 SP1 w/Vista Patch, XML MissionKit, SQL Server Express 2005 SP2 (I decided to use SQL Express rather than the full blown SQL Server AND Express for development purposes - it's proving to be perfect), Photoshop CS2, WinRar 3.7 (you'll need 3.7 for better Vista integration), Resharper, Invirtus VM Optimizer, et al). Much of my development also requires VS2003 (.NET 1.1) which is not supported by MS on Vista. I've therefore established a Virtual PC running XP SP2 as my primary .NET 1.1 dev platform and it's working great. I have it open and running all day long with ne'er a hiccup.
All in all I can say that I'm very pleased with the upgrade and it wasn't the least bit painful. Also, I can honestly say that I enjoy using Vista as a non-administrator (something I had been doing religiously for about 2 years on XP). The periodic UAC warnings aren't the nuisance everyone seems to think they are.
That said, it is important to recognize when things are running under admin privileges and when they're not. For instance, if an application launches following the install, chances are it's running under admin privileges so any settings made aren't going to be for the logged-on user but rather for the administrative account.
I'm loving developing on Vista - it's awesome! 