I agree with guydewdney. In most cases the correct way to get these devices working is to make sure all required drivers/software is installed before the hardware itself.
In this case what you may need to do is remove any trace of this hardware to allow windows to start with a clean slate as it were.
Make sure that the usb lan adapter IS plugged into the USB port (click cancel on any popups that may ask for drivers) Right click on my computer, then select properties. You should shee the system properties popup . . select the hardware tab, then click on device manager.
This will list all devices within your system.
We need to find the network adapter. It will either be listed under the network adapters, or possibily listed as an unknown device, and will have a question mark next to it. Either way, you need to Right click on it and select Uninstall. This should clear out anything relating to this device from the system (I said should . . after all this is Windows we are dealing with)
Now remove the USB device from the PC.
Finally now we have a clean slate, insert the CD that came with the device. If it doesn't automatically run a setup program, then go to my computer and double click on the CD drive. What we are looking for ideally is a file called setup (or setup.exe). This should install all required drivers and software before the device is inserted.
Normally this setup file should be listed in the root directory of the CD, but in some cases you may have to look around a little in the directorys on the CD.
Also in some cases this will not be listed as setup (or setup.exe) but may be called 'Install' or 'Start' or some other name to suggest that it is the file to invoke in order to set up the wireless dongle.
Assuming this goes successfully you should either be prompted to insert the dongle, or if not then once the set up is complete you should be able to insert the dongle and get it working. In some cases a reboot may be required to get things working properly.
NOTE: If the CD does not contain any setup file, then you may have to consult the website of the manufacterer of the device for the latest drivers.
Hope I have been of some help
