MBP 15inch?
Ok... First of all. Up until 4 months ago I still was using a 5 or so year old Tibook, which was techniqly runnin pretty much fine for me, but as I am a design student I wanted to upgrade simply so I could run more at one time and take advantage of the new programs coming out.
Anyway, the point here is that whatever you get now (for the most part) will last easily through most of your undergrad if you take care of it, AND purchase apple care. Trust me... after the 1st year runs out, you are gonna want it. It'll take you through highschool and the beginning of college with a warranty which you will NOT regret. Having the security, is a must. (whether your computer ever needs it or not... freshman year in a dorm though... you never know

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Second...
Why do you keep going back and forth between a 17mbp and a regular mb? The 15 inch mbp is a wonderful machine. I know. I have one
I am a design student, I use a variety or programs you noted. I run Indesign, dreamweaver and basically the whole CS3 suite constantly. My bf has my same computer and plays games on it as well as does video work. Bottom line, the screen realstate is plenty to get along with (yes.. that extra 1.5 inches would be nice sometimes, but my dad has the 17 and with our computers next to eachother the difference isn't as huge as it seems sometimes)
I purchase my computer 4 months ago and have been extrememly happy with it. And it is only a CoreDuo 2.0 ghz 15 mbp. upgraded to 1.5 gig of ram. It doesn't run very hot, and it hasn't given me any problems. The 15 is a nice size... pretty durable so far (compared to my tibook lol) and fits in most basic computer bags as an added bonus.
Anyway, my suggestion to you, is to, like you already decided... to not bother with the 17 inch right now. It's too much computer, and you may be sorry one you get to school and will be carting it everywhere (and sitting it on stupid tiny lecture hall desks) not to mention it is a pretty penny. You are in highschool, you'll want to save your money.
If I were you i'd seriously consider looking at the refurb store. Good stuff, all gone over and checked with the same warranties, I never had a problem with it in the whole time me and my family have purchased from apple.
I purchased my current computer for 1599 total (included the 239 student discount applecare) My boyfriend just purchased a 2.16 ghz with twice video ram coreduo with a gig of ram (although you can find another gig stick or more for under 70 bucks now) for 1500 total with apple care as well.
This computer will still last you for quite some time, and down the line (once you get to undergrad and if for SOME reason you feel you want more.. by then you will probably have a bit saved up if you want to sell your old one (good resale value on maclaptops i noticed) and upgrade you can.)
This way you can chip in less then 1500 .. maybe even half that..(dependin how much your parents are chippin in) and have a lot left over to get copy of CS3 and whatever your heart desires (try to find a student or teacher copy.. it'll be worth the savings if your mom has the credentials to do it)
15-1600 for a very decent and still very new computer, that will run everything you want, give you a bit more screen realstate (my screen is great) keep your future proofed for as long as you need it and with a 3 year warranty.. is a GREAT deal IMO. That's 2300 or 2400 vs 15 or 1600.. that's 7-800 dollar savings between a new computer.. maybe even more if you wait a bit longer. Seems like a lot in this case.
I know this was rambling, but I hope it helped. Good luck on your computer purchases.
PS. CS3 is great

and you could look at a refurb 2.33 ghz intel core2duo (if you are set on the intel2 processor and faster.. it's the same price as the new baseline 2.2 at 1999)