PC can't see Airport wireless network

I have the very first Airport that Apple ever sold. It works fine. Both my MacBook Pro, my G4 desktop and my cable modem have no problems with it.

My husband just bought a used PC. It has a Belkin wireless USB device. It can see my Airport-based wireless network, but it can't log on.

I can think of several reasons why this might be:

1) My Airport, being so old, simply isn't PC compatible.
2) The signal is too weak.
3) The Belkin wireless USB device doesn't have the right software.

I'm suspecting 1, but maybe 2 and 3 as well.

Do I need to replace my Airport?

1) if it wasn't compatible, it wouldn't even see it.
2) strength is fine if it sees it.
3) test by turning off encryption, to see if it likes it without a password. And make sure it has the latest updates from the Belkin site for the wireless usb.

Belkin : Support

> 1) if it wasn't compatible, it wouldn't even see it.

Cool.

2) strength is fine if it sees it.

It only has two bars out of four, but I can fix that by moving the Airport base station and cable modem into the same room with the PC desktop.

3) test by turning off encryption, to see if it likes it without a password. And make sure it has the latest updates from the Belkin site for the wireless usb.

I noticed that the PC had restrictions for what constitutes an acceptable wireless network password. So first I'm going to turn off the Airport's password. If that works, I'll give it a new password that conforms to what the PC wants.

If that doesn't work, I guess I can download the Belkin driver from my MacBook Pro and put it on the PC via flashdrive.

Thanks.

*sigh* Okay, I'm feeling like a complete idiot now because I can't find WHERE to turn off and/or change my Airport password.

I checked under
System Preferences-->Network-->Advanced
but only found an option for "Require Administrator password to control Airport" which is unchecked.

I also tried the Airport Utility and got this message:
"Airport Utility was unable to find any Apple wireless devices. Make sure the Apple wireless device you want to set up is plugged in and in range of your computer, and then click rescan to try again."

Yes, it's plugged in and in range. It's how I'm accessing the Internet right now.

<unrelated whining>Why, oh why, does the family assume that my years of Macintosh usage make me the best qualified person in the house to set up the PC?</unrelated whining>