1. Attach the USB key to a computer running Vista, windows 7 or Server2008. ( if you only have XP, boot the PC from a WinPE CD)
2.Start a command prompt and type DISKPART.
3. Type LIST DISK to locate the Disk number of the USB key. (in this case it a 1GB key, so it must be Disk 2)
4. Now that you knpw the key is DISK 2 run the following commands in diskpart:
5. now just copy the content of your Vista, Windows7 or Server 2008 Installation CD to the USB key and your set to go. (You must of cause use a larger key for that).
For WinPE, create a build following this guide http://kongkuba1.spaces.live.com/blog/cns!EEFF1607E296E5AB!332.entry and then copy the content of the ISO Folder to the USB key
|Content of WinPE build ISO folder||Content of USB key|