also i am planning on mounting it into the floor mounts for the seats which are just little metal rings that asre set in the floor i can probally get a latch for one off anouther car seat amazingly the cabinet dowsnt way all that much more than 2 of my car seats so it shouldnt move if i mount it like that
Hmm, well the difference is, your car seats are specifically designed to be removable, yet still be secure and rigid in the event of a crash. This is done with careful engineering and crash testing with dummies, etc. You're not a dummy, are you?

Unless you are an engineer, and can actually calculate the forces involved and the strength of fasteners and materials required to keep everything anchored safely in the event of a serious crash, I would recommend abandoning this whole idea entirely, as cool as it seems on the surface.
Monitors are quite heavy (even small ones), and I would not trust any home-brewed enclosure to hold one securely. Even if you use actual anchors from your original seats, they MAY keep things from sliding around during normal driving, but there's no guarantee that whatever you use to attach them to the wood, or indeed the wood itself, will keep the CRT from breaking free and being launched thru the windshield with great force, and taking your head with it very easily. You already said that the cab broke apart during moving, and I personally would not trust weakened wood with my life.
One more thing to think about. If by some horrible turn of events, someone is actually killed or maimed in your little funmobile, it is unlikely that your insurance will pay a cent once it is clear that injuries resulted from modifications that YOU personally made to the vehicle. Seriously, if you care at all about your own life (or that of your family or friends) consider having a flip-down LCD panel installed by a professional, with A/V connections on the floor for hooking up a console or a mini PC enclosure. I would suggest tucking the game unit underneath a seat, and strapping it down securely. Make sure you use light-weight gamepads for controls, not heavy home-brewed wooden desktop control panels, or you've got yet another serious decapitation hazard.
Home made cabs are great fun, and are safe enough when sitting motionless in your living room. But the road is no place for large scale DIY gaming, especially at 60+MPH. Am I wrong?