looking for wireless link pc to hifi

ok, got bluetooth and 802.11g and napster on my laptop, that all works
great.

all i want to do is to listen to napster on my "hifi" instead of crappy
laptop speakers without having to run wires around the room. seems
simple enough and an obvious target for wireless

I already have a bluetooth headset which appears in windows as an audio
device, fair enough. All I'm after is a similar product that, instead
of going into a cruddy earpiece, has a couple of plugs I can connect to
the back of my stereo amp.

That should be simple enough but I cannot find such a beast anywhere.
The closest thing I can find are some expensive wifi devices that only
seem to handle MP3 and similar files, not what I want. I'm looking for
something that can be an audio device in the same way the bluetooth
headset does - that way I can use it to listen to Napster etc.
Seems a straigtforward request, any ideas?

Thanks in advance!

Derek