From memory I had only one program that was incompatible which was an old audio editor so no hardship and I made sure to back up everything I felt important. I would recommend running this which will give you good idea on any programs you will have an issue with :
http://windows.microsoft....nloads/upgrade-advisor Had no problems with any VST`s everything survived the transition and was in place with the correct folder structure, exactly as it was in Vista, in fact the first thing I checked once up and running was Sonar and after a quick vst scan I was away and running.
I was one of the few Vista fans, I had very few problems and found it a good OS for my DAW but Win 7 is a step up IMO, I`m sure you won`t regret it.
Good luck and keep us posted on how you get on.
Mark