whs, also regarding the upgrade check, I was saying before that any "tricks" that worked on Vista are not likely to work on Windows 7 since these are well known and MS can easily plug the holes that are known to work. The Software License Manager (slmgr) trick that you linked to has already been mentioned on this forum and many others for (supposedly) extending the Windows 7 RC timeout. The old trick of doing a non-activated install, then an upgrade install with one of the original Vista Upgrade discs has already been plugged on new Vista discs, I believe.
Of course, some enterprising new hacker may find another way around it. For me, this explains why they started using Windows Genuine Advantage (WGA). The only way to surely enforce licensing is when the user "calls home" for service packs, updates and so on.