If you really don't need wireless, don't do it. It's much cheaper and will give you less problems to hook up a 4-port router. Check ebay.
I have this one and it works great:
http://cgi.ebay.com/ws/eBayISAPI.dll...category=44989
Also if the PCs she's hooking up do not have NIC cards, you'll need them too. Get the CAT-5 cables off ebay also. If you get them from the same person, you'll save on shipping. A 50 ft cable goes for $39.99 at CompUSA and for $12.00 on eBay with shipping.
Good luck