Windows 7 makes it very easy (much easier than XP) to change the Product Key - just click the "Change Product Key" link in System Properties.j If you lose your license, yes, your only recourse is to plead your case with Microsoft activation or purchase a new license.  I advise anyone who gets a computer to make a spreadsheet or list of license keys. If you can't get the correct Product Key (the one that came with your system) to activate automatically, then use phone activation - and automated call that takes less than 5 minutes.
I have just had to recover my system but the recovery discs did not solve my problems.  I had to use an OEM copy "upgrade" (which is just a way of fixing the existing installation and is not really an upgrade) which has fixed the problem.  However, I now have a "non-genuine" copy of Windows 7 Home Premium and cannot find the product key.  Does Dell keep a record of the key that came with the pre-loaded software?  Is there anywhere on the Dell site that I can download it from?  Thanks
Another lost key question - Windows 7