Windows Home Server can only share (through it's shares) files that are physically resident on drives directly connected to the server and part of the storage pool. So as described no, you can't do what you want.
The recommended configuration at this time is a variant on the configuration you currently have. You would continue to use Vista Home Premium as your HTPC, but you would configure Vista through registry edits to store recorded media and the DVD library on your server (see
The Green Button for more information).
This configuration would get the media onto your server, stored in shares with (presumably) share duplication turned on. The files would be srreamable (if in a recognized format) by WHS, and would be accessible in the shares from any otehr device capable of dealing with Windows file shares. It would also reduce the data being backed up, which would reduce both the size of the backup database and the amount of time it takes to back up that HTPC.
I'm not on the WHS team, I just post a lot. :)
