My opinion is that using a PCI network card in a Mac is a losing battle. When system updates break it, you can point a finger at neither Apple or the network card manufacturer.

A much cleaner approach, is to use a wireless bridge. This plugs into a computer's ethernet port, and can then join an pre-existing wireless network. Since the computer's ethernet port is used, there is no software to install, the hardware is cross-platform, and multiple machines can be added via a ethernet hub.

I used the ASUS WL-330, which supports 802.11b, and WEP encryption only. The newer version (which I have not used), is shown here: http://tinyurl.com/afglj

There are a myriad of similar products. Some are targeted at the console gaming market--since ethernet ports are now present and used on the Xbox and PS2. The Airport Express will work as one, if in WDS mode--although this is pricey.

Just as an aside, the WL-330 I used, could be powered by a USB port, which negated the need for yet another power socket.