This really should not have been as hard as it was. I tried in vain to take the Windows 7 Ultimate 64-bit ISO, that I had downloaded from MSDN, and put it on a USB HDD that I had laying around. I have just built a new computer and did not bother to buy an optical drive. Unfortunately, my existing Windows machine was 32-bit Windows XP. This meant running any files from the Windows 7 CD (like the boot sector program) was not a possibility.
I tried various tools like UNetbootin, WinToFlash, MultiBootISOs and others. I also tried some tricks with xcopy that did not seem to work. Since I work for Red Hat and am a Linux person, I happened to have a Linux machine at my disposal. Here’s what I found that worked:
- I created a bootable (IMPORTANT!) 4GB primary NTFS partition on my 40GB external USB HDD
- I formatted this partition with NTFS
- I mounted the Windows 7 ISO and the NTFS partition, and copied the files from the ISO to the USB HDD
- I used ms-sys to write a Windows 7 MBR to the USB HDD
There was at least one caveat here. I saw, in a place or two, suggestions to use ms-sys against the partition itself. When running ms-sys against a partition, it complained, so I ran it against the base device (in my case, /dev/sdb).
Hopefully this will help someone out there!