Vista retail boxes did not exist when the Vista Capable problem was running. (Thus, the Vista Capable program: Computers running Win XP Home with "upgrade" potential to Vista once released.)
The common user of computers does not understand how to get their computer specifications from the BIOS bootup, the System information from Control Panel, etc. (And, as experienced users know, Win XP System properties do not always tell you the complete truth anyway.
And, no, Microsoft isn't at fault if other companies write software for only Microsoft products. (Windows x) However, when a company (Microsoft) has, for the past 15 years, constantly had a market share of over 90% (until Dec of 2008), then why should a company support anything but products for the Windows platform, correct? I mean, it is only good, profitable, business.
I am stating the above as a person who only uses Windows because of the simplicity of setup, use, and availability of programs. So, I am not a Microsoft "hater," I just wish another real option existed in the consumer market.