Wow, this thread hasn't been relegated to the archives! Let me try to respond to some of the questions.
Coreypolis's pictures on the first page of this thread show exactly how I pack my gear. Great minds think alike? 
I've been using this bag for a year now and absolutely love it! It holds three lenses with ease (Tamron 28-75 f2.8 attached to the Rebel XT, Tokina 12-24 stored "horizontally", and the Canon 70-200 f4). Still room in there for a hotshoe flash, as well.
Ease of use of the bag continues to be a strong point. It lays flat without rocking, and provides a good work surface for field lens changes. It's sturdy and tough, no rips or tears at any seam, and I do use it fairly regularly.
Laptop compartment: It's a TIGHT fit for my HP zx5000 (15" widescreen), but it goes in. MR2 nice, perhaps its a different fit than your laptop, but I have no scratching up of the surface of my laptop. Maybe I'm just lucky on that one?
Nick5, no scratches at all on the LCD. If you're worried about that, an LCD protector or a small piece of microfiber cloth would protect that LCD while stored.
Hoomer, I have a small "tabletop" tripod that fits in the top compartment, along with the PC connection stuff (USB reader, USB cable, laptop power supply, etc.), a small umbrella, light jacket, and a lunch! It'll hold a lot. A full size tripod can be strapped to the bottom. The strap attachment points are rubberized plastic (I think) instead of nylon, so they are a bit tougher. The tripod straps are sold separately.
Goatee, to get the camera compartment open would require undoing three Fast-Ex fasteners and two zippers. I'm pretty sure i would feel or hear someone undoing all that if they were trying to get at it while on my back, and I move around a lot, so they would have a tough go at it.
4x4rock, that might be a lens too far. Fitting two "tall" lenses would not work, I don't think, unless you really squeezed everything in. The only way I could safely think of would be to put one of them in the top compartment. Your second combination *might* work, but it would take some creative engineering.
A year later, still a great bag. Highly recommended!
BW