for low power systems i would go with debin i guess.
i had it running smoothly on embedded systems with 1ghz ARM cpu and 512 megs of ram (less power than decent smartphone).
even with that configuration you can run minidlna server, trnsmission, ftp, samba and a web server at the same time
to view stuff on your dlna-capable tv:
http://gigatech.co.uk/blog/?p=356