Given that the OS itself allows for it to be reinstalled on a new machine, I just don't see how that's even enforceable. XP think it's in a new machine if/when you put in a new motherboard or do any other "significant" hardware change.
I myself have been using an OEM copy of XP, recently built a whole new machine, nuked the old drive, reinstalled XP in my new machine, and it validated the OEM license just fine.
This part:
This OEM System Builder Channel software requires the assembler to provide end user support for the Windows software and cannot be transferred to another computer once it is installed.
That's the bullshit part. As the builder of my own machine, I don't know what "end user support for the Windows software" means. The "cannot be transferred" part? That's just there to scare you. There's no way for Micro$oft to know, and in any case, as I said, the OS itself already provides for the capability of doing so, in direct violation of those little blurbs above.
So, their OS violates their own license (I'm assuming those blurbs are from some sort of EULA) right out of the box. Nice.
I'd advise getting an OEM copy and throwing all those stupid little "rules" into the winds. Almost all computer shops that sell parts also sell OEM copies that aren't yet installed, and I'm certain Micro$oft knows this quite well. They can't know what your "allowable" system specs are, and I doubt it's going to get installed on multiple machines in sequence, so I really doubt those warnings above even apply to this situation. I'm guessing they only apply to those who build and sell computers.
As long as it's only installed on one machine at a time, I can't see them coming after anyone claiming they're violating the license. Legit copy, single machine = no problem for Micro$oft.