Help with setup for Airport Express with NAS + Airplay

What I want to do is set up my Airport Express for Airplay, my NAS (MyBook Live for Time Machine) and a printer.

However, this seems to be more complex than I assumed.

What may be causing problems is that none of this can live next to the phone line so I have too keep my original router there and effectively 'attach' the airport express via wifi to the internet connected router.

I can get airplay to work, and sometimes I can get the NAS too work too (very slowly) but in Airport Utility it keeps saying 'Device not Found' (see below).

I wonder if anyone could help me out? I'd greatly appreciate it.

You're plugging the NAS into the Express via Ethernet cable, is that right?

Click to expand...

Yep

Is it connecting to a 802.11n router? What make/model?

Click to expand...

Unfortunately not, it's wireless 'g' I think. It's just the crappy free router that came with the broadband.

Is your computer also communicating via Wi-Fi or is it connected to your main router via Ethernet?

Click to expand...

It's just connected over Wifi.

--------

Could I effectively just set it up as it's own little network, is it linking it to the other router that's the problem? Like this guy?