A Deneb USB card and almost any USB wireless adapter. The advantages being the USB card would be useful for other things such as hard drives, USB keys etc.
A Zorro ethernet card such as an X-Surf, Ariadne, A2065 and a wireless bridge such as the linksys WGA54G might be cheaper.
If it is just about getting static data from a PC to an A4000 then the cheapest way would be to use a
IDE->CF adapter and a CF card and "walk" the data over.
