There are a few different ways to install over a network. Probably the easiest way would be using RIS, a feature of Server 2003, MS ofers a free trial. You could in theory download the trial, setup a server and then copy the Vista files to that server and set it up as a remote install. I do that with XP for my PCs I use for testing dfferent setups with, just PXE boot and walk away. Come back at the end of the day and Windows and all of my applications are installed without any input from me.
The only problem you might have is that I am not sure if Vista will work with this yet. But if you have a spare machine around, BTW you will need 2 HDs for this, it is worth a shot.