Below you will find the Realtek RTL8187B Windows Driver for both Windows 7 as well as Windows Vista. There are two versions of the driver. There is Windows Vista as well as a Windows 7 driver for this. Search this website for more drivers if this is not what you are looking for.
There are a number of Realtek drivers so if you don’t have a Realtek RTL8187B then simply check what else is on the website.