WIFI Audio Player - am I dreaming?

I have an Asus WL-500g (original) that I have been trying to turn into a network audio player (using diy usb soundcard as output).

I have tried a number of different versions of openwrt (x-wrt, dd-wrt, openwrt) and have always run into problems with space. By the time I have installed the firmware, got samba working and maybe ftp too, then installed USB and audio packages its beginning to get full!

The ASUS WL-500g has only Flash: 4MB RAM: 16MB

Am I dreaming?

Maybe I could use an install that is pretty small, has usb featured ...?:(