Yes, there are slightly fewer than a kajillion USB-to-serial cables out there. You should be able to pop down to your favorite local electronics store and pick one up. Or if you prefer web shopping you can put "USB to serial cable" in your favorite search engine. Or just check the product list in your favorite online electronics store.
If you have Vista, make sure the one you pick has a Vista driver for it.
Make sure you get one with adequate length. The ones that are most readily available are only 18" to 24" long. If you are picking it up locally, take your the serial cable from your Magellan along to make sure you get the right gender on the serial connector end of the cable.
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