Best bag for camera and laptop as hand luggage/work bag?

I’m traveling later next week with a new camera (EOS 40D and 17–85) and a MacBook. I’m trying to make the best choice for a new bag. I’ll be carrying them onto the plane (hopefully with a few more small items) and I’ll need to carry them to work most days. Should I try for one bag or two separate ones? Recommendations? I’m currently using a smallish laptop shoulder bag and a LowePro TLZ, which just about stash together in sports bag, but I don’t fancy carrying this everywhere. Maybe a Crumpler that takes both but isn’t too big? Help!