I have a custom build PC connected to the net via a netgear wireless router. My dads PC is also connected via this same router but wirelessly.
In order to do this i used my PC i.e. the one that is connected directly to the router to bring up the options screen for my router (this is done thru your web browser normally and instructions should be in the manual for the router. it usually involves browsing for the isp number e.g. 123.44.5.6). At this point make sure you have the wireless signal enabled, normally done by checking a box somewhere.
Then what i did was to set up a psp or pre shared password between my router and my dads pc. it doesnt have to be complicated, i just used 1234567890. this was then used to pair my dads pc with my router much in the same way as you pair bluetooth phones. once this is done you dont usually have to enter the psp again as it is sent automaticaly when you open the browser on your now hopefully wirelessly connected laptop.
as the above answer stated, the connection between your laptop and the router is nothing to do with your pc except for the part where you use it to set up your router. if you have no pc wired to the router i think you will have to connect using a cable to the laptop in order to set up the wireless connection then disconnect it once it is done.
hope this is of help to you.
lee, August 2008