Have you read the instruction manual available from diablocam.com?
It looks like you might have to manually install the drivers.
Try going into Device Manager, right click on My Computer and go to properties, then I think with XP you go into Hardware and click on Device Manager.
Look for a yellow exclamation mark or anything like Twin Base listed.
Right click on this and click on Update Driver.
Click No to connect to the internet and select manually install.
Next click to include this location in your search, click on the folder icon and navigate to to Setup Twinbase and the Driver folder, it might be listed differently.
Click next and let Windows install the driver.
Please post back with the results ot if you have any problems.