If you wife's computer uses a 4 port wireless router you can connect the printer to both computers using that, wireless or wired, if your printer is net-workable. If not you can go for a print server. The other choice is to treat your wife computer as a server and yours as a client, for this you will need two network cards or network outlets on each PC and the server will have to be turned on for you to connect to the printer.
You can connect 2 PC's using a crossover RJ45 network cable.
If you do not have a network printer you can connect the printer to the 4 port router using a USB TO LAN RJ45 Ethernet 10Mb/100Mb Network Adapter
http://www.amazon.co.uk/USB-LAN01-Usb-lan-RJ45/dp/B000CCZP88
You may have to put a second Ethernet card in your PC:-
http://www.amazon.co.uk/D-Link-DFE-530TX-100Mbps-Ethernet-Adapter/dp/B00004SYNX
Whatever you do never ever try to connect 2 PC's together using a USB cable, you will do serious damage.
See here for a lot more options:-
http://www.ehow.com/search.aspx?s=How+to+Share+a+Printer
http://www.ehow.com/how_4449672_share-printer-between-desktop-wireless.html