laptop wireless with desktop

I have a laptop and a desktop both using windows xp. I would like to know if there is a way for me to hook up my desktop to my laptop via lan cable and share the wireless connection that my laptop uses. I am using a linksys wireless g router with the laptop and i would like it if i could do this wouthout having to purchase additional hardware. Could someone walk me through a step by step instruction for this. If even possible.