I think that counts corporate developers, and corporations are not switching to Vista yet. And anything you write for XP will port to Vista, so there is no rea

I think that counts corporate developers, and corporations are not switching to Vista yet. And anything you write for XP will port to Vista, so there is no reason to target Vista specifically. To port to Vista, you may have to add a manifest file to your software and possibly rewrite some parts like installer scripts, rethink some of the flow of the program due to user prompts that might popup and scare the user, and update documentation to warn users. But developers had the same problem of having to test in Windows XP separately from Windows 2000 and Windows 98 when XP came out. Microsoft's own latest software remains compatible with Windows XP, and while Vista is one extra operating system you will have to test for, Virtual Machines let you run multiple operating systems on one computer. That's not to say I miss my Vista system that I ditched for my mac. :)