Since Jim was asking about substrate need, I figured I would post some of the calculators I have run across. It may save some of you a little bit of time...
Substrate Calculator http://www.plantedtank.net/substratecalculator.html
Cool General Tank Calculator http://boonedocks.net/fishtank/ftweb.php
Commercial Fertilizer Calculator http://www.fishfriend.com/fertfriend.html
KH Calculator http://dataguru.org/misc/aquarium/CalKH.asp
Chuck's Planted Aquaria Calculator http://www.csd.net/~cgadd/aqua/art_p...osage_calc.htm
Chuck's Planted Aquaria Calculator - downloadable version http://www.csd.net/~cgadd/aqua/art_plant_aquacalc.htm
I don't know how accurate some of these are since I am not a chemist. I mainly use Chuck's Calculator and the KH Calculator. Let me know if you know of any others and I will add them to the list!