I'm going to agree with everyone else here too (Sarah, Rex, Frog, Mark, et al.)...keep the lights low...learn how to get the tank in balance with fertilizing and your feeding routine before you jump to the higher light-high tech setup. A planted tank with the bells and whistles will cost a lot in the short run...but wise choices and planning will keep costs down in the LONG run. Do read Rex's guide...its chock full of great info that will help you out in both the short and long run.
Start with low light species and work your way up...you will get frustrated with plant deaths, algae, etc. Get a good grasp of your plants' needs now, then the hobby will be much easier and enjoyable for you later.
IMO a 90g needs pressurized co2...again, its another investment you need to plan for...as well as a good canister filter (an Eheim 2028 or a Filstar XP3). Talk with Rex about putting together a beer regulator system which will be cheaper than purchasing a commercial regulator/solenoid. If you choose the latter, I recomend the Azoo.
Good luck and ask some questions if Rex's guide confuses you.