JIP
No longer a newbie, moving up!
Any of the LowePro bags that are marked "AW" are from my own personal experience extremely water tight. I have one of the Orion packs that have the camera comparment with a daypackon top and I took it on a trip to Mexico. One day wihle we were out there was a rainstorm of monsoon proportions and I was stuck in it for a good 15-20 minutes and not a drop got inside my bag. Of course i did have the raincover deployed and it kept everything dry.