What would be a good, small, single camera body and lens + flash bag?

Preferably backpack; I have a lowepro flipside 400 AW and I love its capacity because I can just about take everything everywhere, but during the semester I carry around that bag (7D+Tammy 28-75+Canon 85/1.8+580EXII+60mm macro+tubes+filters, chargers, batteries, other odds and ends, soon to be a grip and sigma 50/1.4 as well) and a messenger back with my school stuff (laptop, notebook, folder, between 1 and 3 textbooks). I can get it all on me nice and balanced, and it's actually not so terrible muscle-wise, but I sometimes get temporary pounding headaches which probably isn't good. I don't really have anywhere super safe to store my gear besides my bag, so I'm leery about just loading and unloading my bag on a regular basis.

So, what would be a good, light, protected back-pack style bag that could handle a 7D with mounted lens and my 580 and not much more than that (another lens tops)? I've seen some small bags that fit this description but they don't seem all that secure, which is a problem.

Why not the Lowepro Classified 140? Shoulder bag, but made for a camera plus mounted lens, and a speedlite? Built like a tank.

what about the fastpack 200?

Hm, I'll look into both. The fastpack seems a little more alluring because of my school bag being a messenger bag already. I'm really impressed with the Lowepro I have now so I'm sure either of those would work nicely. Thanks =)

fastpack 100 would fit the bill

and p.s. don't bring your kitchen sink to school. =P

Could take pictures with my kitchen sink I would

Single body with its mounted lens and a flash? A backpack's going to be kind of big for that. I carry a 5D2/24-70 L and 580EX in a Domke F5Xc shoulder/belt bag.

you could look into getting one of those inserts (tenba, domke). then you could put it in any bag you already have.

it doesn't really make sense to lug everything with you every time you have to go out. can you get a lock box or a safe in your room? do you just not trust your roommate?

It's not that it's going to be stolen, just possibly moved/bumped around more than I feel comfortable. I don't mind leaving things in my bag (so long as mild bumps aren't going to be an issue), but I'm paranoid otherwise. Ideally I would like the option to take only a small kit most of the time.

Oh, and another reason I prefer backpack over shoulder bag is I bike ride with my gear sometimes, and messenger bags and bikes don't mix so well. I think I'll look into the fastpack 250; that way I can just take everything in one bag on light days and otherwise it's still convenient. Anyone know if it'll hold a single non-ridiculous text book as well as a laptop (my laptop is 12", so it'll definitely fit, possibly even in the top compartment)? It's hard to judge size from the picture, but it looks like it might be a little tight.

I've just got the Tamrac Velocity 7x. I've only gone out with it once, but I like it.
350D + 55-250 + 18-55 and it's nice and cosy.
You might need the 8x