I'm a latecomer to this thread - I was out hiking this weekend, and just got home.

In addition to all the great information everyone else gave you, a good book never hurts. I'd highly recommend Karen Berger's Hiking and Backpacking: A Complete Guide. It's a good, basic book that's fairly balanced between "lightweight" and "traditional" gear and style recommendations. If you're defintely wanting to go toward the lightweight end of the spectrum, her Hiking Light Handbook is a very balanced and accessible manual, too.

As far as your question about the Aether 70, it's a great pack - if you're planning to carry 40 or 50 pounds of traditional (i.e., bulky) gear and do some winter camping. If you're more traditional, and can hold to a load of 30 pounds or less, take a look at the Osprey Kestrel series (probably the 58 or 68), which weigh a pound and a half less, but have fairly equivalent feature sets and robust, adjustable suspensions. I used a Kestrel 58 for a 32 pound load of traditional gear (Hubba tent, Thermarest pad, stainless steel pots, white gas stove, fleece jacket, etc.), and always found it comfortable. I replaced it with a Kestrel 48 as my load lightened to under 25 pounds (Carbon Reflex tent, Pocket Rocket and Titan kettle, NeoAir, down jacket, etc.) and found it equally comfortable (the lighter load was also more comfortable.)

Get the rest of your gear figured out first, though - then buy the right-sized pack with the supportive-enough suspension to hold it all and ride comfortably. If it's the Aether, you won't be sorry, either.