I use a tablet without a screen, and it takes some getting use to, but once you get the hang of it, it is easy.
I use the http://wacom.com/en/Products/Intuos.aspx The medium size is only $350 and comes with a good bit of programs.
The tablets with screens seem like a big waste of money to me. The cheapest wacom screened tablet I could find was the http://wacom.com/en/Products/InteractiveDisplays/DTU-1631.aspx, going for $1250.
My suggestion is to buy the Intuos 4, practice with it, and you will be using it with ease in no time.
What size would you recommend? I'm thinking medium simply because with me getting a new computer soon as well, I can really save a few bucks. But I also want quality and effectiveness. It seems like the small is just too small, and medium is a little small too. If it's really as easy as you say though, I might go for it. It just seems like it will be hard to do detailing with it.
By the way, using it for fun.