It sounds like the one running xp is the router. It has a usb connection to the internet (via some sort of modem, what type of modem, we don't know) and I guess it also has a wired interface that can export it's internet connection.

It's simiilar to the 2nd diagram on this page, except it's wired, not wireless?

http://www.microsoft.com/windowsxp/u...tup/adhoc.mspx

Did you set up the xp computer with Internet Connection Sharing?

The only other "gotcha" would be that you might need a crossover network cable if you are connecting one computer directly to the other, but most modern nics can detect swapped tx/rx signals and deal with them.

If both computers have wireless, do it using the wireless method on that page.

You should be able to do it no matter which computer has the modem connected to it.

-David