I have a new Dell Latitude E6500 and use a home WiFi network to connect to the Internet. I have occasion to use a Dell FP2100 external monitor. When I connect the monitor to the E6500 using an older VGA-type cable, the WiFi signal is strong and constant, but if I use the DVI connection, via and adapter connected to the DisplayPort, the WiFi signal is weak and erratic (although the monitor image looks better).
The wireless router is a Cisco/Linksys WRT160N. It is set on mixed mode and automatically sets the channel.