If the usb ports weren't already active it wouldn't be showing up in XP. The following might help here.
"If you plug in your USB flash drive and you are not prompted to install a driver for the new hardware then drivers may already be installed, however they may be the wrong drivers or out of date. To delete the drivers so that you can install the most recent and correct version open the
Start menu and right-click on
Computer and select
Properties. Click on
Device Manager and then expand
Universal Serial Buscontrollers to display all the USB devices connected to your computer. Right-click on your USB flash drive (it must be plugged into your computer to show up here) and then select
Uninstall. You may need to uninstall and reinstall
Genetic USB Hub and other USB controllers as well to fix the problem. Once the device has been uninstalled right-click on
Universal Serial Bus controllers and then select
Scan for hardware changes and this will begin the new driver installation process described at the beginning of this article. It is worth checking the web site of your USB flash drive manufacturer, as the latest software driver may be available there for download."
http://www.windowsvistamagazine.com...ta-does-not-recognise-my-usb-flash-drive.html
Another article is titled: "Make Windows see any USB flash drive as local disk"
http://www.lancelhoff.com/2008/06/19/make-windows-see-any-usb-flash-drive-as-local-disk/
These are a few ideas to try out since you know the drive works in XP.