17 Inches is pretty big to be lugging around day to day to school. Not just the weight, but the size of the laptop would be annoying fast.
I wouldnt go with anything over 15.4, as its just more dead weight, considering a 8700M GT isnt going to be able to power many games at 1680x1050. If you pair a 8600/8700 with the 1280x800 screen you will be golden. The only game so far that has giving me problems is Crysis, but even then I still play it all on high with shadows on low and shaders at medium + 4x AF with my 8600GT(any other game out there it plays maxed out).
One thing Id look into is a ASUS EEPC if youre going to be needing a laptop for day to day mobile use such as school. Very cheap(500ish?), light weight, and very small which is perfect for school.
Overall its a great laptop and a great deal(never had a problem with my old satellite), but Id just go with something smaller and lighter for your intended use.
edit; just checked the link and newegg says its $1400, which makes it a bad buy IMO
heres a pretty good deal
Newegg.com - Acer Aspire AS5920-6574 NoteBook Intel Core 2 Duo T8100(2.10GHz) 15.4" Wide XGA 3GB Memory DDR2 667 250GB HDD 5400rpm DVD Super Multi NVIDIA GeForce 8600M GT - Laptops / Notebooks