I must have owned close to 50 bags over the last four years. It's a never ending struggle for me to find the perfect one. I'm currently sporting a Tamrac Ultra Pro 17 (the second one I've owned!), and a Lowepro Classified 160AW. I've given up on backpacks, as I prefer to travel light if I'm doing a lot of walking.
The best advice I can give, is to find a bag which you can afford, which will fit the required amount of equipment in, and that isn't offensive to your eyes, and then buy it. Simple. The fastpack bags are great value, and you won't go far wrong with one those. I had the 350, and it was absolutely fine.
I've found, for what it's worth, that Kata and Tamrac seem to make the best bags for me. Not sure why that is, but there you go. Most of the big brands make decent enough quality items. There aren't many "bad" bags out there to be honest.
Most backpacks will take the amount of equipment you mentioned, just make sure the laptop section is big enough (screen size) for the laptop you have, and away you go!
