quick update, went and got tht unit.
enabled UPnP media server on the D-Link 313 NAS, the unit then appears under 'media servers' on the WDTV. Have watched a couple of avi's and streaming no problems.
Bit of a novice here, but before i enabled the UPnP on the NAS, i could still see my avi's under 'network shares' on the WDTV. Could start my shows, but they shuttered and were crap. Maybe someone with more clues can explain this...anyway all looks good so far...giddy up