Are all the netbooks going to have the same specs?
In our case, to have the hibernation feature pre-enabled, we installed Ubermix to one netbook, then made a Clonezilla image of that. We then used USB sticks with Clonezilla and the image on them. It was incredibly fast, and plugging the usb sticks was easier than plugging in all the netbooks to ethernet wires for PXE boot.
Not sure if you could get the Ubermix installer to start through PXE and NFS, but I am quite sure you can get Clonezilla to do that, and automate it to deploy the Clonezilla image of Ubermix that you create based on one of your netbooks.