Welcome to Sysnative!
A link to the thread would be great if at all possible.
What precisely is wrong with his .net? If we can't reinstall Windows then we need really to aim for a fix. And the processes which handle updating, in some respects - operating, installation and reinstallation, turning on & off, etc. etc. are all the same. So when one breaks often they all break.
At any rate, complete destructive reinstallation of .net is no longer recommended, especially for the latest versions of .net (versions 1.0, 1.1, 2.0 etc, especially on Windows XP are a completely different game). What we now tend to do is turn on diagnostic logfile writing, re-fail the installation, grab the logfiles, and fix whatever's wrong.
Richard