Need suggestions for medium sized camera backpack

[canonfoto]

I will be going to Ecuador this summer; I need a medium sized camera backpack from which I can quickly deploy and put away lenses. It has to be weatherproof and has to carry 3 lenses, a laptop, and a camera body.

Suggestions?

thanks
cf

[francongphotography]

have you heard of the lowepro fastpack? it's pretty good. but you might need to bring a waterproof cover for that if you're going to ecuador

[gkphoto]

the Kata 3n1 sling backpacks are really nice. that is my normal bag that I have. I have it setup so that everything is accessible from the side flap. I have the large one, in the main compartment I have 30d with grip, generally with the 24-105L attached, the 17-40L, a 70-300 tamron, 50 f1.4, 580ExII. the other compartments have room for batteries and cleaning supplies, filters etc. really great bag and access is great. it also comes with a waterproof cover. I also have one of the Lowepro Slingshot 202 which is also an awesome bag, but it is nice to have 2 straps if going hiking.

good luck in your search, if you want pictures of how i have my Kata setup just let me know.