Make sure the monitor is actually bolted down and not just sitting there, and check the rest of the cabinet for loose objects, and then lay it down in the back of the truck.
Be careful of one thing. Some cabinets (Centipede style cabinets and Crystal Castle style cabinets, and others), have window-breaker designs, and can slide forward and break the rear window of your truck if you don't stick a piece of wood in the way (or do what I do with these, lay down a blanket and transport them on their side). You start to get paranoid about these after you bash out the sliding glass window on a brand new truck and have to pay $300 to replace it.
Standing up games should be reserved for two or more games, as it is hard to securely stand up one game, but easy to do two and easier to do three (strap them to each other and then strap them down).