I run a virtualised copy of Windows XP with VirtualBox, and one thing that I couldn’t get running was the network adapter, or ethernet controller. There’s a free Windows program that helps you with this problem though: Everest. Download and install Everest, and it should tell you the manufacturer and model number of your card (or anything about your computer’s specifications for that matter). Now just go to the manufacturer’s website and get the right driver for your system!
How To Find Out What Network Adapter You Have