futureproof
I currently have a MB that i bought in late 07. When I but a computer I generally try to anticipate the possibility of what I may be doing with it come 4 or 5 years from now. I have been a member of these forums since then and when people ask questions like yours. they also discern do you absolutly need it immediatly? or can you wait til the New OSX lion comes out?
I would suggest waiting til the new OSX Lion comes out so that way your buying a computer that is designed for that OS. you also get better specs. that will last you at least four years.
the computer I bought in 07 still works just as good as it did the day i bought it.
like i said above, with regaurds to the 13 or 15 i would suggest you consider the possiblity of what you may due with the computer. doesnt mean you will fullfil those ideas, but it means if you do game for example the occassional game, you will have a computer that can handle it. or need to use FCP it will handle that. granted most of the time you will just use it as you describe, but you need to come prepared for what you may grow into computer wise.