Robert Fenner's "Conscientious Marine Aquarist" is a good read also. A lot of folks might say to ignore the "cycling with fish" part of it, but otherwise it's a good read for starters.
Take your time, do the reseacrh, read the experiences folks have here, and buy the equip you need for your goals - the first time around. Nothing like having to buy another "anything" 'cause you rushed to get started, didn't know the ultimate goals for your tank, and bought lesser stuff. A 125 is a good start.
Anyway, good luck, keep us posted and let folks here help you with equip purchases when you need. And most of all, welcome to AA!