Plug the adapter's USB cable into your computer. 

You will then be prompted with the Found New Hardware wizard.

At the first screen, select No not this time, and click Next.

At the next screen, choose Install from a list or specific location.

Insert the CD provided with the adapter. In the Found New Hardware wizard, browse to the CD drive, choose the folder for USB_serial_WinXP, and choose Next.

The wizard will update the driver. Click Finish to complete the driver update.

If you now browse to Device Manager, you will see that the Prolific Adapter has been installed under Ports (COM & LPT), and a COM port has been assigned.

User-added image

In the ActivManager Control Panel, check the Connections tab to ensure that the same COM port is selected, and click Connect before rebooting your computer. 

Should you experience any problems, disconnect all devices from your computer, uninstall the ActivDriver and then reinstall it, making sure that you select USB + Serial during the installation process.