router to receive internet and send to pc?

[f2t]

I have wireless internet in my house and have just built a new desktop pc. I want to get internet on the pc but would rather not use up slots on my motherboard for a pci wireless card.

I have a spare wireless router. Can i use it to receive the signal then connect to my pc via ethernet?

 

[f2t]

no I cant really run a wire to where it is unfortunately.
The spare modem is a Tiscali modem, can provide specifics later when I get home.

Id rather not add in another card if I can avoid it and I heard usb ones are not great. Other than that, what about the things that run over a power network?