WDTV Live streaming wirelessly

I am considering buying WDTV Live to stream movies at home - my home router is a BT Home Hub 3.0 which is wireless-N standard, the same as the WDTV and I have a NAS storage device connected to the router.  The router will be no more than 5 metres from the WDTV with no thick walls in-between - will I be able to wirelessly stream 1080p standard HD movies from the NAS device through the router to the WDTV without buffering?  Or would I have to connect using an ethernet cable?

If it’s only 5 metres, I’d definitely use wire.