can you only use them in cars with isofix points? We have an ancient ford escort and we need to upgrade ds' car seat, but we want to get a new car in the next year or so. Are isofix seats better because they pin the seat to the car frame? It sounds like they are to me, but I'm fairly sure our car doesn't have isofix points (how can you tell?) but it'd be a waste to buy one seat now and in a few months another one with isofix.