[shoreline]

You need to set a login script under the extenders profile to map the drives using UNC paths for every extender you own, search for netlogon, my scipt is as follows:

net use m: /delete /yes
net use m: "\\NAS\videos1" /user:xbox360 babbage
net use n: /delete /yes
net use n: "\\NAS\videos2" /user:xbox360 babbage
net use o: /delete /yes
net use o: "\\NAS\videos3" /user:xbox360 babbage

This sets up the shares to be accessible when the extender logs in.