I'm in High School, and I have a G4 tower with a 17" display (paid myself), with a 22" widescreen display coming soon (will also be paid for myself). I also have a Thinkpad (selling) and a TiBook 500 (just came in this weekend).
This setup is above and beyond most familys' setups, never mind a high school student, and let me tell you: There's no HS aged task that can slow my setup. A MBP is an amazing machine, but think clearly of your priorities that come with your age. I have to think about a Car, Insurance and Gas soon, as well as an AP exam and other expenses. My setup I have cost me about $900 total (G4 tower, current 17" and TiBook + Thinkpad) and I can handle any task. Windows? why get an intel mac when I have a perfectly fine Thinkpad? Movie editing? Thats the G4's specialty. Portability? TiBook or Thinkpad are perfectly fine for the road, with the TiBook's battery lasting longer of course.
I'm pretty confident all of my machines can handle Browser Tabs up the wahoo, for about 3 grand less than your setup. Even though your setup is future-proof (G4's are aging and so is the Pentium III in the T23), I think you should wait on such a huge purchase. Besides being very expensive, you dont want your machines being a year or two old when you get to college. The displays will be bigger and brighter, and the Macbooks faster and shinier. Most studios have to second-guess purchasing a setup like that, let alone a HS student. And with the lack of Pro Apps being used; why not spring for a cheap G4 or something like that tiill college? That way you could even take it to school without as much fear of it getting robbed, and you'd still have all the productivity of the MBP sans the Intel capabilities.
Believe me, when the novelty of the new machines wears off, and after all your friends have seen it and gawked at the 30" ACD, you'll begin to think you paid a little too much.
my $.02