|Is it generally possible to boot from USB?|
I mean, can you select this in the BIOS?
If so, the easiest way is, to either create a bootable USB stick and copying the windows installation CD to that USB stick, to install it from there, or you buy a USB CDROM and boot the installation CD from that CDROM drive.
To make an installation of windows over the network by booting from the network a.s.o. is not that easy and is not made up in let's say 5 minutes.
But if you really interested in howto install windows from a network, here is a short guidance:
How to: Install Windows Over Network