Any universal USB cable with a mini usb plug on one end will work fine. If you don't have an extra one from a previously purchased camera or smart phone, you can purchase one from a office supply store or in the electronic area in a dept. store.
Before update your gps please create a backup using windows explorer, here is a link for the procedure.
http://www.tomtomforums.com/t17864-how-backup-contents-your-unit-computer-how-restore.html
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Report map errors at http://www.tomtom.com/mapshare/tools/
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Backup your gps --- for details see
http://uk.support.tomtom.com/app/answers/minor_detail/a_id/13354/
or
http://www.tomtomforums.com/general-tomtom-discussion/17864-how-backup-contents-your-unit-computer.html
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