Windows Vista? I think you're going to be stuck there. If your cradle is the Kenwood one (label underneath reads KHD-USB1) then there were no drivers released since 2003. The PhatHack USB 1.1 Drivers are the latest available ones, although I have an outstanding support issue with Cypress (manufacturers of the cradle chipset) where there ARE newer TPP200 drivers but that don't work.
Your best option would be to buy a USB 2.0 cradle, which Vista should support natively.