The only reason why Microsoft would rather sell Vista than XP on new computers is because the longer they sell XP, the longer they will have to support it. The more updates, service packs, and the longer they have to make software that is backwards compatible with it, rather than focusing on new technologies in Vista/Windows 7. They make as much money off a sale of XP as they do Vista, but XP costs more to maintain.
If Windows developers aren't writing code for Vista, it won't magically work on Windows 7, so if your software is XP only, its time to find a new supplier!
In short, Windows Vista is the future of the Windows platform, and it is a very bright future! As far as most people that I talk to that claim they don't like Vista, most of them can't seem to articulate why, or they just say "That's what I've heard". The MS bashers have done a great job spreading anti-Vista propaganda, but few can articulate any real problems with the OS.
Long Live Microsoft! (And Linux, and Apple)