As far as I know the "legality" of selling NFR software (software that you received as a gift but did NOT sign any agreement with the software vendor) has never been tested in court. Microsoft has sued folks over NFD (not for distribution) software where the recipient signed an agreement with Microsoft over distribution, and that seems to be enforceable. In any case, most software licensing and sales issues are contractual issues that are decided in lawsuits and not in criminal court.
There has been at least on MAJOR software reseller that was selling NFR-version Microsoft Server software. Microsoft knew about it and didn't seem to take any legal action. But Microsoft, obviously, has other potential avenues available to it to apply pressure to a large software reseller.
From a real-life standpoint, most auction houses and other venues attempt to ban the sale of NFR software. In many cases, though, simply removing a sticker on a box makes it near-impossible to determine whether it's NFR or not.
Microsoft employees that I've queried over the years usually reply this way about NFR:
"Do anything you want with it, but we don't want to see a sales invoice with it listed".
As for me:
I take it for what the sticker says. I don't sell it. I do give it to my clients sometimes, or I use it in my office. Frankly, there are even questions about that, since older Microsoft EULAs stated that NFR was "only for testing and evaluation". The latest Vista EULA, as I recall, has changed that and allows NFR software to actually be "used".
