Lowepro Primus is a brilliant pack - but the camera compartment is not very big and doesn't have a lot of dividers. You won't be able to fit all your stuff in there. K10D with Sigma 70-200 mounted, kit lens, TC, some smaller bits, that's it, I think.
Very nice for 1-2 days, top compartment big enough to take a *small* sleeping bag and change of clothes, very comfortable harness (for a photo backpack...), can be used with hydration bladder, but way too small for what you want to do.
Tamrac is bigger but harness is crap.
If you want something for 2 week trip - I don't think *any* photo bag is good.
Get a proper trekking backpack, top-load holster, a couple of lens cases and padded pouches for your flash and other stuff.
It will be more expensive but it will work