Thank you all for the help. I'll give you the short story first, aford was right.
aford10 :
If it works in safe mode, it could be a driver issue. Safe mode uses windows default drivers.
Getting the latest driver seems to have solved my problem. I haven't pushed it very far but I just watched 20 minutes + commercials on Hulu in full screen glory with no lock ups and no problems. 1 successful test doesn't necessarily prove anything, but I'm going to take it as a good sign.
I had suspected it might be a driver / windows 7 RC x64 issue but had been running into dead ends. At aford's suggestion I went back down the driver rabbit hole again. I rolled back the drivers and installed the version that Gigabyte lists as the most current on their website. Crash. I installed the version that came on the CD with the GPU. Crash. I ran Windows Update and it found a more recent version than either of those. Crash. All of this I had tried before. This time I chased it a little further looking all around for more drivers. Finally I installed and opened the "Catalyst Control Center" AMD software. Found an option in there to check for software and driver updates and it took me to the following web site:
http://support.amd.com/us/gpudownload/Pages/index.aspx
After picking my graphics card information it took me to an updated set of CCC software which included ... another new driver! The driver details that work (updated for Windows 7 x64, and I believe Vista too) are:
Driver Provider: ATI Technologies Inc.
Driver Date: 8/13/2009
Driver Version: 8.650.0.0
Thanks again. scj, I hope you get your problem straightened out soon.