As netbooks get more popular and optical drives become less and less of an assumption, there are many times when a USB install of an operating system is a far better choice than the old DVD/CD we know and love.
When working with USB keys, whether to install or run the OS itself, in the past it was quite the chore and involved much wrestling of vendor utilities.
Thankfully, the world has changed and nowadays installing from USB is a rather easy process — provided you have a working Windows install or can borrow one.
For Windows 7, it all begins by going to this page and downloading the Windows 7 USB/DVD Download Tool.
http://www.zdnet.com.au/installing-windows-7-from-usb-339326019.htm