TC4200 does have the Powered USB port I looked it up on the HP site (links provided below). My TC1100 has 2 USB ports, I do have a Craddle and two ways to connect it. Tablet Powered USB and an additional USB with mini AC Adaptor. If you are unsure of which specific craddle to purchase, you could probably contact HP for help. The second link is for accessories.

HP Compaq tc4200 Tablet PC - North America/U.S. QuickSpecs

HP Compaq tc4200 Tablet PC Options & accessories

Good luck.