Download oscdimg.exe and put it in C:\Windows\System32 (or anywhere on your path).
Start a command shell with elevated privileges.
D:\>oscdimg -bd:\win7pro\expandedSetup\boot\etfsboot.com -u2 -h -m -lWIN_EN_DVD D:\win7pro\expandedSetup\ D:\win7pro.iso
OSCDIMG 2.54 CD-ROM and DVD-ROM Premastering Utility
Copyright (C) Microsoft, 1993-2007. All rights reserved.
Licensed only for producing Microsoft authorized content.
Scanning source tree (500 files in 48 directories)
Scanning source tree complete (874 files in 201 directories)
Computing directory information complete
Image file is 2520809472 bytes
Writing 874 files in 201 directories to D:\win7pro.iso
100% complete
Final image file is 2523011072 bytes
Done.
D:\>
Use imgburn to write the iso to disc.
