You'll need to approach your System Administrator and make sure that your NB has been allocated a connection through whatever security system they are using.
They could be using WEP or MAC Addressing or a combination of both that is preventing a connection being made through the WiFi connection.
Or it could be something simple like you need to run the WiFi Network Setup Wizard and configure the Wireless connection to your network. Each WiFi Network has it's own unique connection method and you need to build up a range of different user profiles to allow a NB to connect to different WiFi Connections.
The directions to do this should be in the users manual but I very much doubt that your companies network will be wide open so the IT Section should be the ones setting up the WiFi connection into their LAN.
As far as other connections are concerned the help Files in XP will show you exactly how to setup a WiFi Connection.
Col