Windows 7: Install windows 7 on USB external hard drive

I am trying to install windows 7 on an usb attached external hard drive, into a secondary partition. I've tryed installing from an ISO file mounted as a virtual drive, by extracting the files and running the setup file and by booting from the ISO file of a DVD/DR disc. I choose custom install and everytime I get to the point of selecting my installation drive, I get the message "Windows 7 cannot be installed to a USB partioned Hard drive"

I've searvhed help sites and discussion grouips for hours and have not found a single reference to this problem.

I'm currently running Windows 7 beta, but do not want to do an upgrade as I have several existing problems (virus and registry related) so when I'm ready to do the install I want it to be a new install vs an upgrade. Before I wipe my entire drive for the new install, I wanted to install and run the latest win 7 OS on my secondary hard drive to make sure I like it, and if I have any major issues.

Any suggestions greatly appreciated!

Hi,
I think the message speaks for itself. Windows cannot be installed to a USB hard drive.

MS doesn't want to make WIndows 7 portable enough that people can carry it around in their pocket to run on any computer.

Your best bet is to do a Custom install over your RC. If you run from the desktop it will save your files (and nothing else) in a window.old folder for distribution.

However if you have virus or other corruption concerns which cause you to not want those files transferred from the RC, then save your files you want, nuke the drive using DBAN, then boot from the installer, select Custom install, use Drive Options to create a new partition, format and install Windows 7 clean.

You may need to use a workaround if you nuke the drive: Clean Install with a Upgrade Windows 7 Version

Try this: Unplug power supply and data cable of your internal HDD. Start computer with USB HDD connected and with Win 7 Installation DVD in. Hope you'll succeed.

sorry wrong post

If you are wanting to load Windows 7 to a USB device,, this is what you will need.
Good luck!

it should be noted that running your OS from a portable USB hdd will be painfully slow.

It hasn't been accomplished according to Google for any Windows OS except XP, and that tutorial is one of the most complicated around.

The hurdle is USB, since you can connect the external using a SATA/IDE cable and achieve it, of course.

Actually, it has been accomplished,, I don't care what Google says.
You can run Vista from a USB drive, and 7 (though not stable) does work.
Although, yes, Winbuilder has made the process a bit more complicated.

XP (or more appropriately), BartPE or UBCD4WIN both work very well off of a fast USB drive.
When and where it will be slow depends on the system it is being run on.

The system in my specs, runs it extremely well. BartPE has been a life saver on more than a thousand occasions, fixing XP, Vista and 7.

Quite honestly,, I don't (literally) leave home without my thumb drive.

Interesting, Tepid. Have you actually run Vista or Windows 7 from a USB external drive?

At least once a month, someone stops in to claim that they can do it. But they are never able to show that it was actually done.

This results in many futile attempts on the part of end-users to try this, so we have to tell them not to waste their time as there is no record that it has actually been done.

Then someone claims it can be done and the cycle begins again.