I have been flashingin Win 7 since the initial Beta as well w/o issue. I have flashed a CDMA Diamond and GSM TP2.
For those of you having issues flashing in Win 7 Professional, Enterprise, or Ultimate:
Check out Windows XP Mode. Microsoft gives you the ability to run a virtual fully licensed copy of XP. BUT YOU MUST HAVE PROFESSIONAL, ENTERPRISE, or ULTIMATE!!!
http://www.microsoft.com/windows/vir.../download.aspx