lol @ "does mIRC have to be Vista Compatible"
Yes. I use Vista. So do you apparently. mIRC has to be Vista compatible, otherwise it won't work. That's what compatibility means.
RE: "Well my computer/Vista didnt like that." Guess why? because you setup mIRC in a way that is incompatible with Vista. That's why your data is now stored in AppData, because Vista does not allow data stored in Program Files. So yes, mIRC needs to be Vista compatible because otherwise.. it won't be compatible with Vista (meaning it won't work), and we'd be getting more complaints like the above. The question is: do you want mIRC to work in Vista or not? You probably do, so the answer to the original question should be obvious.