Today I installed Windows 7 Ultimate Beta from a Transcend JetFlash USB Flash disk drive in dual boot mode with Windows Vista.

Here are the steps you need to follow in order to install Windows 7 Beta from a USB drive:

1) Make your USB drive bootable using DiskPart-

a) Open the command prompt and type diskpart
b) At the diskpart prompt, type “list disk” to get the USB drive number as seen by the OS. For example, you may see a value of Disk 1 for the USB drive. Then, continue with the commands listed in the next steps.
c) select disk 1
d) clean
e) create partition primary
f) select partition 1
g) active
h) format fs=fat32
i) assign

2) Now that your USB drive is bootable, make sure the Boot from USB option is enabled in the BIOS.

3) Extract the contents of the Windows 7 Beta ISO to a folder such as C:\Windows7

4) Copy all the files and folders from the DVD to the root of the USB drive by using xcopy-

xcopy c:\windows7\*.* /s/e/f X:\ where X is the drive letter of the USB disk

5) Restart your computer and choose to boot from the USB drive

6) Windows 7 Setup should automatically start. Complete the installation process. Make sure you choose another drive letter under the custom installation options if you want to dual boot.

7) Ensure to run Windows Updates in order to download the latest drivers for your system. (nVidia has a pre-release version of the display driver “WDDM 1.0″ for Windows 7 Beta)