How to connect powermac G5 to wireless network

Hi,

I've bought a powermac G5 (april, 2005) without an airport card. If I want I connect it wireless, what is the best and cheapest way to do it? Is it:

(A to buy an airport card with antenna

(B to buy an airport express station and connect it via Ethernet

Or (C to buy an third party antenna to connect to the router

So again: is it possible, what works the best, and what is the cheapest.

NB. My wireless network is going via a time capsule. The router is on the first floor and my Mac is on the third.

Thanks in advance

Fabian

Powermac G5, dual core 2,3 MHz, 2.5 gb ram, 230 gb hard drive

PowerMac, Mac OS X (10.4.11)