linux software based 802.11b mp3 receiver

I've got an old laptop (P166, 80MB RAM, limited HD) which I've set up
as a wireless access point in my apartment. I'm using another laptop
as my primary computer, and I move around with it a lot due to the
freedom of 802.11b.

Only problem is, the speakers on laptops suck - I'd like to be able to
hook up some decent speakers to my laptop, without losing the
mobility. I found this device:

http://www.gridenabled.com/gc-wl.html

which would essentially act as a wireless receiver, and would allow me
to play mp3's which are stored on my mobile laptop, controlled by my
mobile laptop, but on speakers which are not hard-wired to the mobile
laptop - all without having to attach an x10-like device to the laptop
(it has 802.11b built in, so no extra hanging peripherals).

What I'd like to know is, can the same thing be achieved using a linux
based software solution? Ideally, I'd be able to open winamp on my
mobile windows laptop, load a special plugin, and the output would be
directed to the 802.11 interface rather than the laptop speakers.
Then my wireless access point laptop, running redhat, would be
connected to the speakers, and the sound would come out there
instead...

That may be optimistic, but I'm thinking something similar is possible
with the combination of a shoutcast stream and some sort of network
based remote control for xmms...

Any ideas? I could just buy the device, but it's like $270 =P

Jon