Well if anyone had any doubt I can tell you Vista and Cubase 6 (along with the projectmix I/O) is working like a dream here! Ironically the Cubase 5 engine would not respond sometimes when closing the window but now I do technically NOT meet minimum system requirements and it works faster and never crashes.
Saves me upgrade money going over to Windows 7 and I never had any problems with Vista anyways this last year. The first year was hell but worked all right after that.
Decided to write this since no one wrote their experiences about C6 on a Vista OS and wanted to see one. So now I have a C6 copy and confirm I had no problems whatsoever installing and the program is working faster and more bugfree then Cubase 5.