Was wondering if anyone was familiar with a backpack that met the following criteria:

• Waterproof (in a downpour)
• Sidepockets large enough to securely hold a 32oz Nalgene bottle:
  
  
• Sidepockets wide enough to securely hold a mini U-lock (I like being able to reach back and pull it out rather than having to open up the bag)
• "MP3 pocket" situated inside the main compartment near the top of the bag (for the iPod; I don't like having it mingle with my keys and other items)
• Big enough to hold a 17" laptop

Understandably, this is quite specific. If you have even a close recommendation, I'd appreciate it.

Thanks.