If you want a device to trigger specific scenes and cues then using an Akai LPK25 USB laptop keyboard (about £30) works well. I have it set up to use the black keys to trigger laser content and the white keys to trigger video content. There is a direct USB connection from the keyboard to the PC and the keyboard takes power via USB. You map controls in MM to MIDI notes. You can stick labels onto the keys to remind you what each one is programmed to do.