I don't see Vista listed on the list of supported operating systems for Inventor:
http://usa.autodesk.com/adsk/servlet/index?siteID=123112&id=8410923
On the other hand, they don't officially mention XP Home Edition, and it runs fine.
On hardware problems: some people will have them, some people won't. It really isn't fair to judge the OS's hardware autodetection based on trying it on one machine. The same is true of Linux - sometimes hardware works out of the box, sometimes it doesn't. Apple gets off easy, since they control the hardware (although not all of the peripherals).
Likewise, "new program bugs" will cause problems for some, but not everyone. Large businesses can't afford to take that risk, but many individuals can.
I'm not a mac person, but I found this pretty humorous:
http://news.com.com/1606-2-6190253.html