Ive been on Vista for some time now, and encountered zero problems...
UNTIL... (Had to be one...)
Until I installed Alcohol 120% to burn some data-backup CDs...
Starforce went ape****, and now I cannot get SH3 to install and function. Might have to format, to get it working agin.
Bottom line, if you have the post-starforce version of SH3, go for it. Vista is great. If you have an early copy, like I do, make sure you dont install ANY form of virtual drive.