I just used this to make a Win7 USB install thumb drive. I added a few files and then backed it all up using the restore function for the next time I want to throw it on a USB stick and install Win7 somewhere. It worked great. Thanks Josh.
While on his page check out his other software. Looks like if you have trashed you activation, he may have a solution for that, too.
Do you need a copy of Windows Ultimate with SP1-U? ('u' means update to sp1)
Windows 7 Ultimate SP1-U ISO:
English 32-bit
English 64-bit