I see no-one has responded so I'll have a go..

You should not need to install drivers for the USB hubs themselves, unless the Windows drivers are corrupt or missing. Look in Device Manager for any question marks. This page might help:
http://www.microsoft.com/whdc/system/bus/USB/USBFAQ_intro.mspx

Thanks for taking the time to answer.

I did not find anything there to help me, and the hub in the monitor is still not working. I have tried some more alternatives in order to locate the error:

I connected the same hub (monitor) with the same USB cable to another computer, a Thinkpad R52, where it works just fine. The driver used there was usbhub.sys, a part of the standard Microsoft USB drivers. On my computer (Thinkpad T42) I have the same driver in the same version, and this driver is being used by other devices, for instance the USB Root Hubs on my laptop and docking station.

So the device (USB hub) works, the cable works, the driver works, my computer works, other USB devices on my computer works. Still my computer does not recognize the device, and I suspect the error is in my Thinkpad T42, not the USB hub/monitor. Hence this should be moved to another forum on another site :-)