In courses 5119 and 5105 they keep on talking about the different ways of deploying Vista images. Either by DVD or by Network share or by USB.
Taking into respect that your images will be several GB big, even in compressed state, USB sounds like a good alternative when using unswitched networks or slow 10/100 MB ones.
If you're not using PXE and SMS to push out the images you will need a version of Windows PE to help along the way. Now I'm a minimalist and hate having a CD with PE and a USB disk with my image. Why not have it both on the usb and boot from it directly?
Before you embark on that journey keep in mind that not all computers boot from USB! So make sure your environment is going to support your new deployment mechanism! Otherwise many hours will be going down the drain as your great and fancy bootable drive will never get used!
Before you go around all the forums and create a bootable usb disk with HP tools and windows 98 remember that you have the power of Vista at your finger tips. Well, should have! The new version of DiskPart that comes with the AIK detects usb flash disks and usb hard disks as if they were fixed disks. Thus you can clean them, repartition them, set them to active and format them with your desired FileSystem (NTFS). Once prepped all you need to do is copy the contents of your favourite WinPE ISO or WinRE ISO (see post from yesterday) onto the disk and you're up and running.
VistaPC Guy has a great step by step article on putting WinPE on your usb. read it here: