I want a light bag for carrying only my essentials: a ThinkPad X200 with 9-cell battery, an iPad 1, a bottle of water, some small accessories/gadgets, sunglasses, headphones, and a wallet.

If I buy a massive bag, I'll fill all of the pockets available and my back and knees will not be happy

So... I'm drawn to the Ristretto line. The problem is that there are three Ristrettos! I'm pretty sure that the Ristretto for iPad won't have room for my ThinkPad but without having the bag in front of me, it's impossible to be sure. Could the ThinkPad be comfortably carried in either of the smaller Ristrettos or should I buy the "Ristretto for 13" Macbook"?

Incidentally, my iPad 1 is in a Marware case that significantly increases its dimensions (see here).