Some controls just wouldn't work in design mode in Vista/Win7 and MS weren't going to fix/shim them. I didn't have problems compiling VB6 code on earlier operating systems and running them in Vista/Win7, but development does have some issues beyond the initial installation of it. I persisted/worked around it for the most part, as I had freedom to do so, but if I was doing work (as in $$$ or assignments), I'd probably run it in a VM (if I had an edition of Windows that permitted it) to be safe.
Maybe your google-fu will find solutions for that too, but just be wary, some of your fights to get things working (particularly as I say, some controls in design mode,) might cost you time. Depends how rigid the assignments end up being, and how much control you have.