use the windows print sharing is probably the easiest and cheapest solution but you would always have to turn on the pc that it is connected to in order to print.
if you want to print at any time from any pc then you need print server on your network
http://www.newegg.com/Product/Produc...server&x=0&y=0 a wireless print server
http://www.newegg.com/Product/Produc...rchResult=True might be a nice option seeing as you have wireless devices aleady.
just make sure you get the right interface - usb / parallel