Here it is 2013, and i am still using my 2006 Macbook Pro. I have taken great care of it and it still looks like new. I just bought a new battery, and a new 128GB SSD Crucual M500 hard drive. AMAZING is what I will tell you about the newer SSD drives. My iPhoto library opens instantly, my login time is down from 15 seconds to 4. Yep, 4 seconds. BTW, I am running on 10.6.8 - as that is the latest OS I can run on my core duo 2.16.
I debated buying a new Macbook Pro, but the $$ are huge, and I can still do everything I need to do. Streaming video is perfect, and I can edit pictures the same as I have ever been able to do. I realize how much more vibrant and bright the new LED backlit displays are, but I think the contrast is tweaked too high on them, and when I need to be picky, I hook up my external 23" LCD to my full size DVI port.
So if anyone out there is struggling over deciding to spend a massive amount of dough or stay put with what you have, I will tell you there is no shame in keeping what you have. Just spend 100 bucks on a current generation SSD hard drive, and make sure your battery is good and you'll feel like you have a new machine.
By the way, I am not knocking the sweet new MBP's and Air's, etc....but they are truly expensive, and not all of us can swing it, or are willing to go into debt for them.