RV Towing Best Vehicle? Just don't know

We are really thinking about getting an RV when the economy gets better, but what is the best vehicle to have for rv towing? You really have to have a vehicle that is big enough so it doesn't burn it up. Is there some kind of chart to figure this out? Talk about making someone feel stupid. I just really have no idea if our truck is big enough. If anyone has a clue let me know.