Run Ubuntu from Windows via a portable USB Hard drive

The following tutorial explains how to easily run a "full installation of Ubuntu" directly from a Windows PC without the need to reboot. Our example is run from a portable USB Hard drive that we can take with us anywhere. Through emulation, Ubuntu can be run from the portable device using a host Windows 98, NT, XP, 2000 or Vista computer to launch the emulator. This enables the user to run Ubuntu and Windows simultaneously. Were using Qemu hardware emulation software with the Kqemu accelerator to accomplish this.

Necessities:

Computer (running Windows)
USB Hard-Drive (at least 3GB of free space)
Ubuntu ISO
UQemu.exe (contains Qemu, Kqemu and a special batch file)

The Portable Qemu Ubuntu Creation Process:

Create a folder named PQUbuntu on your portable USB hard drive
Download and extract the files from the UQemu.exe to your PQUbuntu folder
Download the latest Ubuntu ISO and move it to the PQUbuntu folder
Double click the create-n-run.bat (Once presented with the Ubuntu launcher, select the first option to start or install Ubuntu)
Click install from the Ubuntu desktop and continue through the installation process. Proceed to install to hda -3.2GB Qemu Harddisk (the install will take some time "20-60 minutes")
Once installation has completed, select the option to restart. Then close the Qemu window once Ubuntu has shutdown
Now, simply click the Ubuntu.bat file whenever you wish to run Ubuntu from the USB device

Performance Notes:

You can edit the -m value in the Ubuntu.bat file to use up to half of your system memory ( However, I don't recommend using more than 512MB) QEMU currently limits the max guest ram size to 2047 MB

Other important tips:

Use Ctrl+Alt+f to toggle between window and full screen mode

Use Ctrl+Alt+Esc to move from Ubuntu to Windows

Update 9/24/07: Kqemu now works from Windows Vista