When I install XP on my dell and try to create a

Did you reformat the hard drive? You may not have loaded the drivers for your network adapter. (In that case, your sound probably won't work either, and possibly other devices.)
If you check in the device manager (see here), you'll see it is disabled or not installed.
You need to locate your Drivers cd, or download them from Dell and install the drivers for your network adapter, reboot your system, and it should appear in the device manager and function. Here's a basic troubleshooter that will help you to sort this out, and here's a more advanced version in case you run into other problems. This excellent tutorial will help you to update the drivers for your system.

I hope this information allows you to resolve this issue. If you need further assistance, please post back with a comment to this thread.
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