I want wi-fi access for my 2010 2.8Ghz mac pro. Should I buy Airport Extreme base station?

I do not have the following:

1) An AirPort card fitted - really expensive call-out charge and part
2) Would rather not run a cable throughout house to the router downstairs, as it is rented accomodation.

Will the Airport Extreme base station, pick up the wi-fi from downstairs?
Or do i definately need an ethernet cable draped all over the house to the Virgin Media router for a cheaper option?

(Have tried using a usb ralink but it has stopped working and want something more substantial)

What's the best option?

Thanks for any advice! It's such a headache knowing what to do!

AirPort Express

AirPort Express

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