games for 4 and 5yo?

[faddle]

Am travelling to devon from Yorkshire this weekend, around a 7 hour drive, not counting any toilet breaks. We are setting off at 2am so hopefully by the time the kids wake up we will only have a couple of hours of "are we nearly there yet" before we arrive.
What sort of entertainments should I prepare to avoid strangling the little buggers them getting bored?
I have the DVD thingy set up, and also have some aquadraw mini mats for them to fight over share. Anyone have any good, inexpensive ways to prevent arguments, violence etc?

I sing v loudly to ease the boredom - eye spy daft things, big pot of grapes to nibble. We used to have those reusable sticker things, the plasticy ones and they stick them on their windows - dh really liked that game . Then stop. Let them run round like puppies and then go again - the hours will feel like weeks minutes!! Enjoy