The Realtek RTL8187SE is a mini PCI-e 802.11b/g wireless LAN card and is found in many netbooks and some laptops, for example, some versions of the MSI Wind U100. Recent versions of Ubuntu have a native driver for this card, but it can be unreliable. An alternative is to install the Windows version of the driver using ndiswrapper.
This guide explains how to install the Windows XP version of the RTL8187SE driver using the graphical frontend for ndiswrapper on Ubuntu 9.10.
Start by installing the graphical version of ndiswrapper with your favourite package manager. In the Ubuntu Software Centre you can find it under "Windows Wireless Drivers" and in other package managers you can find it under "ndisgtk". It can be installed either from the on-line repository's or from the Ubuntu 9.10 CD.
Next you will need to download the Windows XP driver for the card. You can find this by going to the Realtek website. Save the ZIP file to a convenient location (e.g. the desktop), right click on it and choose "Extract Here". A folder should be extracted with a name which is something like "RTL8187SE_WindowsDriver_XP_.....".
Now, go to System->Administration and then "Windows Wireless Drivers". After entering your password you should see the following window.
Choose "Install New Driver".
Click on the browse button. Navigate to the folder you extracted from the ZIP file earlier. Inside it you should find another folder called "RTL8187SE". Inside that folder you should see another folder called "WinXP". Finally, inside that folder should be three files - chose the one called "net8187se.inf".
Press "Install" to go back to the main window. This step may take a few seconds to complete.
Click "Close" and then restart your computer. After restarting you should be able to use the network manager to scan for, and connect to, wireless networks.