This little problem came up today when a friend asked me to look at a recently purchased ASUS netbook. The transaction for the device came via eBay and the seller had inadvertently (in an attempt to securely erase their data before shipping the device) erased the entire hard drive, recovery partition and all.
This particular device had no optical drive so as to reinstall Windows from OEM DVD. So, after search on the we for an answer I came across this little article on how to create a bootable USB Drive and then transfer the contents of a Windows installation DVD onto it to use to resurrect the netbook. Great article, brief, and to the point. Here is the entire URL:
http://www.intowindows.com/how-to-install-windows-7vista-from-usb-drive-detailed-100-working-guide/