Well, I can say that I have configured a set of AirPort Express base stations to service a PC-only household. Each AirPort Express is connected via Ethernet to a LinkSys router, which is in turn connected to a Motorola SurfBoard cable modem. The AirPort express units provide wireless coverage in individual rooms of the house in question (the walls are thick radio sponges).

Each AirPort Express is configured with a password to join the network. On a Mac, you'll connect using the base stations using the password; on a PC, you'll have to key in the hexadecimal equivalent, which the AirPort configuration utility will give you.

It seems to work fine.

At my house, I have an older AirPort base station, the 802.11b-only "snow" one, connected directly to a Motorola cable modem It's configured to require a password to connect to the network, AND the network is hidden, so you have to type its name as well. Connecting via an 802.11b card on a PC laptop entails typing the network name and (again) the hexadecimal equivalent password.

Works for me; ymmv.

For what it's worth, I'm going to insert a newer LinkSys router into my home equation, since apparently it can handle DynDNS stuff, which is cool.
--
Aargh