<<< I would like to check my connection speed >>>
Try this speed test site - click here
<<< My desktop that is connected by cables has always stated 100.0 Mbps on the icon in the system tray. My laptop which connects wirelessly gives varying speeds ranging from 54 Mbps(best) down to 12 Mbps(worst). >>>
These speeds are not those of your broadband internet connection. The standard speed at which a "wired" ethernet network runs is 100Mbps, so this is the speed at which your network adapter is communicating with the router. Similarly, the optimum speed for an 802.11g wireless network is 54Mbps, so this is the speed at which your Wireless Network Adapter is communicating with the router.