For Windows XP
Usually its really easy to disable and enable a lan connection in windows7, but its not the same in windows xp. Once you disable the LAN the process gets off the taskbar. Then you have to go all the way to the Network Connections folder and enable it.
An easy way would be to make a short-cut of it from the Network Connections folder onto your desktop, by right clicking and creating a shortcut. Now rename it the way you like. Now enable/disable is as simple as right clicking that icon and clicking on Enable/Disable.
This is not such a great how to but it helps 😉