If we hijack the Windows bandwagon from Microsoft, then Microsoft will be like a BIOS vendor when it comes to Windows. Anyone remember "IBM compatible PC"?
If almost everybody stays with XP and DirectX 9 and doesn't move on to Vista, then Windows XP+DX9 could become a defacto standard that even Microsoft can't get rid of! Just like Intel can't get rid of x86 - they tried and failed with their Itanic, and when IBM tried to switch to MCA.
Then the jobs of people doing Wine, Crossover office, Cedega and more become a lot easier - they have a fixed target instead of multiple moving targets.
Be realistic and ignore the fanboys out there, there are many valid reasons for wanting Windows. XP will continue to make a good substitute for Vista, unless more and more people start switching to Vista.
But there is no Linux substitute for Windows yet, BUT if enough people stick to XP, it becomes far more likely for there to be one.
Just a look at Vista will tell you that Microsoft is no longer improving things significantly or meaningfully, so we might as well freeze Windows, and be able to spend more time and resources on innovating elsewhere.
So everyone, start telling Dell, HP et all to preload and sell XP instead of Vista, and tell your friends to insist on XP instead of Vista.
There are already other valid reasons to prefer XP to Vista, for example: A Cost Analysis of Windows Vista Content Protection
If I copy something I do not deprive the owners access to their original/copy.
Whereas if I steal something I deprive them of access to it.
In fact, introducing more restrictive copyright laws or increasing copyright terms could arguably be closer to stealing (than copying), as it does reduce/remove the public's access to things that once would have rightfully been theirs.
So who are the real thieves?
If it's worth hacking on well, it's worth hacking on for money.