The purpose of this tool is to have a single MAC address same for LAN and WiFi interface, so you could connect to the same network as one computer from both interfaces. The LAN interface has higher priority - speeds could be much higher of course
OneMac is able to detect link change and if it detects LAN cable connected, it sets LAN as primary (and vice versa). When WiFi is not set as primary, it can be turned off completely to save battery.
No other tool on the net worked for me (automatic wifi disabling on cable connect). So this is my response
Compatible with WIndows XP/Vista/7 x32/x64 non-UAC/UAC