Thanks for the info, but as everything with Windows, it's not that easy. For more info about Windows attributes/ permissions, read:
http://support.microsoft.com/kb/326549
To remove the read-only attribute, click on the Start button > Run... button > type in "cmd" > type in: attrib -R /S /D full-path-to-directory (substitute in the full path to the HTMLPurifier directory). Don't you just luv Windows.... Hope that helps
Note: Even after you perform the attrib command, when you right click any HTMLPurifier folder, it will still show "read-only." However, all of its files have been correctly modified and TinyMCE will now correctly work in IE7.... YEAH!!!