I doubt it, i beleive in the FAQ he states how rubbish he thinks Vista is, infact here's a quote:
The program was designed for any Windows version and does not depend on a special Windows version as long as the graphics card drivers are fully functional and bug-free. It runs great under Windows 2000 and XP, it even also runs great on Windows NT4.0. However Vista introduced a couple of major internal changes that might have introduced incompatiblities between older Windows versions. It is unclear if these changes conflict with NoLimits or not. At least I do not give a F.CK about if NoLimits works under Vista or not, because I am not responsible for these incompatibilities and the last thing I will do is to install Vista to check out if NoLimits works or not. Haven't you read the Vista EULA? If you are familiar with German language, I highly recommend to check out this page:
Ich spiele nicht mehr mit
also very interesting:
DRM in Windows Vista
A cost analysis of Windows Vista content protection
In a lot of cases the graphics card drivers that ship with the Windows CD/DVD are not fully functional or have beta quality. The same goes for new graphics cards that come out. I suggest to test the demo on your machine before you buy the program and try to update your display card's drivers to the most recent version if you experience any problems.
http://www.nolimitscoaster.de/ [FAQ section]
However, with more and more user using vista he may be swayed, i don't honestly know.