A good quick app i use often is this one here:

http://www.nirsoft.net/utils/wireles...k_watcher.html

It shows you pretty fast all the devices on your network. runs in the background and uses hardly any resources. i have a cheap router and live near a trailor park that is overrun with people using reaver to hack routers. In the end the only way i could stop them was by only allowing an exact number of devices on my network and blocking all devices except the ones i registered on my router. Now this is not foolproof!!! your mac addresses can be spoofed. but it was enuff for me to keep those guys off my network. That lil app up there is great tho. checkitout and that company has tons of useful lil apps that use very little resources.