What's wrong with my Airport?

[chrisnelson at mac.com]

I'm hoping somebody else might have some ideas what might be wrong with 
my Airport connection to my cable modem.

Last week, I bought Airport cards for my iBook and my Cube. The iBook 
works perfectly with my Linksys base station. Unfortunately, the Cube 
is suffering from abysmal transfer rates. Where the iBook is 
transferring data from the internet at about 1.6 MB megabits/sec, the 
Cube is only getting transfer rates of a few hundred kilobits per 
second- not that much faster than a modem!

I've tried swapping the card out with the one in the iBook, and it 
makes no difference. The Airport antenna wires in the Cube do not seem 
to be obviously damaged or crimped in any way.

My cube is well out of warranty. Am I correct in assuming that Apple 
won't help me without charging me for the service, even though I've 
never had the chance to use the Airport before? What could I expect to 
be charged by Apple for any repairs?