The HL-3070CW has an ethernet port to print from if one does not wish to use the wireless option. According to the installation disc I have for the 3070, it is compatible with Macs running as far back as OS 10.3.9. You haven't really specified what OS you are running on your "old" Mac, so it's somewhat difficult to recommend what you really need, and what actually works with your systems.
There's also the HL-3040CN, which is the entry-level colour laser in the Brother lineup, and is currently going for $249.99 (source-> Brother website). This one does not have any wireless capabilities, and relies solely on ethernet.