Not sure how to force windows to use a specific driver.....
Here's how I would do it in Vista (64-bit)..
1. With the cable
not connected to the PC, install the Prolific driver from the ZIP file I described above
2. Connect the cable to the PC
3. In Device Manager, find and double-click the entry for the cable
4. On the "Driver" tab, click the "Update Driver" button
5. Select "Browse my computer for driver software"
6. Select "Let me pick from a list of device drivers on my computer"
7. Uncheck the "Show compatible hardware" box
8. If the Prolific driver has been installed, you should be able to pick it from the displayed Manufacturer and Model lists
If you cannot select the Prolific driver in #8 above, try this instead of steps 7 and 8:
1. Click the "Have Disk" button
2. Browse to:
\Windows\System32\DriverStore\FileRepository\ser2pl.inf_XXXXX
(XXXXX on my machine is 8105e9be)
3. Select the ser2pl.inf file and click Open
4. Continue with the installation (I'm not going further than that point on my machine)