first a couple of things.
if your router has wireless support your laptop (if new) should have a wireless adapter built in, so basically your destop computer can be wirely plugged into the router and your laptop shoud "connect wirelessly" to your adapter
so this is how your set up should look like
--cable-- = - cablemodem - = linksys router = ----- wire----- desktop
--cable-- = - cablemodem - = linksys router = ))wireless))) laptop
you need read up a bit, here are some links that will have info you needmanual for wireless configuration
(select the proper revision for your router and check user manual)
configure wireless network for vista
read up and if you have any questions post back.
hope that helps.