This may be of some use to those with WIN7...
Use a free tool from MS to make a bootable USB drive from virtually any ISO.... including the WIN7 CD with some tweaking.
http://www.maximumpc.com/article/web..._download_tool
FTA: If you want to use it for any/all ISO's and bypass the Win7 security you'll also need this tweak:
http://www.withinwindows.com/2009/11...h-custom-isos/
Explanation of all this in the articles.
EDIT: Also looks like the tool works on XP, as long as you have a few other things installed (.net and some other MS tool listed in the MS article).