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First, don't generalise your topic title, make it specific to your query.

Secondly, you answered your own question.
I don't really do anything other than web browsing

Short answer: you're just wanting to own the newest model, you don't need it, save your money.
 
I cannot figure it out by my self, so I want to ask some of you.

- I've got this macbook pro 15,4" 2.53 core 2 duo from 2009, but I really want to have one of the new ones, but I cannot figure it out, if I should sell my old MBP, and then buy a new, or should I just keep this one.
I dont really do anything other than web browsing, facebook, youtube, schoolwork and all that standard stuff on my laptop.

- So what to do? is it worth buying a newer version, or is it waste of money?

With the recent trackpad update giving you inertial like scrolling, if you really want buy one of the new AC adapters and you wouldn't even be able to tell.

Only thing that would be bothersome and different is the non dynamic GPU switching and battery life.
 
get a new mac blue tooth track pad with al the new features they are pretty cool

you really have no need for a new computer
 
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