Just note that Boot Camp Assistant is picky and in principle looks for only full retail licenses. For other versions, you may have to perform part of the install manually. Full retail licenses are the only ones that are 100% compliant with the licenses.
Is it locked to one PC once installed?
Per the license, yes. In practice not really.
Also per the license, you are supposed to resell the system you install OEM/System Builder on to an unrelated third party. That is the letter of the license, but may or not be enforced or apply in your country of residence.
Retail product keys are generally more lenient in terms of unassisted re-activation on new hardware since they are licensed to be transferable. Many have transferred OEM licenses, despite the license explicitly not allowing that, but it typically involves calling Microsoft to activate.
As Granny indicated in passing, you may even be able to use a retail upgrade version by following this guide.
http://www.winsupersite.com/article/windows-7/clean-install-windows-7-with-upgrade-media.aspx As long as
you are satisfied that you qualify for the upgrade pricing, there is nothing stopping you from installing that way.
That would seem to indicate that when I get my new laptop I would not be able to uninstall it on this one and install it on the new one.
As I said above, the license specifically prohibits it, but in practice they usually will allow you to activate. According to some folks the precedent in Germany is such that the license can even be removed from one computer, resold to a third party, and re-installed.
B