I really can vouch for the Linksys WRT54G series. There is a whole range of models, but be sure to pick one that is supported by 3rd party firmware like OpenWRT.
I’ve got 3 WRT54Gs (v1.1, v2 and GL) and they all work like a charm.
Even without the 3rd party firmware they forward multicasts etc. in the LAN just fine.