I recently picked up a KATA backpack for precisely the same needs. www.kata-bags.com/productFRM2HS.asp


My camera is a little smaller (XTi) but you could put the 7D/24-70 2.8 combo in horizontally with room for maybe another lens or two depending on the size. The top pocket is big enough fro most standard books, though a full sized text book will probably not fit. I find this bag perfect for taking to school.