http://cgi.ebay.com/PC66-256MB-SODIMM-Apple-G3-iMac-Lombard-Wallstreet-/400129682681
These seem cheap if they do in fact work on Wallstreets (they need low density memory). I see …
Make sure you have the appropriate network extension installed!
Since your Ethernet card is an Apple one, you just need the Apple Ethernet LC extension which can be found here.