actually it could be in their best interests. As long as they get OEMs to pre-install vista, they make twice as much money as most users are going to shell out for a copy of xp which does not seem to have dropped in price with the introduction of its replacement. I suspect that MS may keep extending their support of xp for the remainder of vista's run to keep people buying.
They would have legal complaints made against them if that were the case. People would object to paying for something they don't want just to enable them to buy what they do want. That was already a major issue in the DOJ vs Microsoft anti-trust case and why Dell, ASUS and Walmart has begun selling Linux to home users.
Then they would complain about not being able to play HD DVDs. Back porting all the DRM from Vista to allow that would be a major task. NOT back porting the DRM while allowing the playing of HD DVDs would cause more legal issues from Vista users.
I think that Microsoft must learn several things:
1/ That the OEMs who they sell to are not their real customers. The end user IS the customer.
2/ Big Brother behaviour annoys their customers. Stop the call home "features".
3/ DRM progressively annoys their customers. The MPAA and the RIAA are not their customers. Forcing DRM on your customers to please these organizations annoys their customers
4/ Incompatibility with standards and competing products also increasingly annoys their customers
5/ Integrating things to block out competitors makes an unweildy mess with issues. Individual programs should BE individual programs not joined together at the hip to please marketings desire to destroy competition. Customers who don't like a specific Windows program should be able to uninstall it. (IE and media player for two)
6/ The market has a maximum size and it is approaching that. Indefinite income growth is not possible. Adapt to that.
7/ You can't successfully hijack everything new in the computer field.
Microsofts Big Brother behaviour made me cease to buy new products from them and begin the migration to Linux (my Windows 2000 computer hasn't booted in days now).
Others are finding that Vista is the step too far and have begun to migrate to Linux, BSD or Apple (or just stay with their old systems longer). That is why Microsoft has been compelled to keep XP on the market longer than planned, to
attempt to hold onto those customers who are saying "enough already" and "this is MY computer NOT YOURS".