I just wanna have this "How to" in my blog, even for myself. :-)
What you need:
Step 1 - Formatting the Drive Using the command prompt, we'll use the diskpart utility. [BTW: This will erase all data on your USB drive]
Step 2: Make the Drive Bootable Next we’ll use the bootsect utility that comes on the Windows 7 disk to make the flash drive bootable. Type the followinf in the same command window that you were using in Step 1:
Step 3: Copy the installation DVD files to the USB drive Using Windows explorer or any other tool to copy all of the files on your DVD on to the formatted flash drive.
Step 4: Set your BIOS to boot from USB Don't forget to check that your computer has USB boot enabled in the BIOS config.
We're done!, just plug in your USB and install Windows 7! :-)