Mikey said:
Basically I am askin you guys to help bulid my tank hahaha...
We'll be right there!

Welcome to the club. Sounds like a a nice tank to be starting with! A 125 should make you happy for quite a while, as long as you plan it out well, and it sounds like you're doing just that.
I have done some research but i still am quite unsure what i should be getting to keep the tank running tip top.. I understand somewhat about the sump/refugiums but.. Protein skimmers...Calcium Reactors.... ro/di unit.....Koralias....
One of the first things you need to decide, before answering any of your equipment questions, is "What do you plan to keep in the tank?" Take a look at other tanks, oogle stuff at the LFS, get opinions from others, and see what kind of tanks turn your reef-crank. If that's an all softy tank, you'll need less flow, less light, and little or no calcium/alkalinity supplementation. If you're aiming for a turbulent fore-reef SPS tank, or something with light-loving, fast-growing clams you'll need a whole different set of conditions - lots more light, more flow, and a serious Ca/alk dosing plan.
In general:
A sump is always a great idea, and I'd encourage you to read about them (
www.melevsreef.com has some good basic descriptions and construction ideas) to decide how to design yours. The best way to get one is to make one - get a used glass tank or a cheap new one on sale, and silicone some glass dividers into it to make your dream-sump.
A skimmer is a must. There are some pretty affordable brands of decent needlewheel skimmers available now. Choose this before designing your sump, so you make sure there's room for it.
Do all your plumbing with flexible PVC pipe ("spa-flex") or rigid PVC (or a combination of the two. Don't use vinyl tubing or corrugated aquarium hose. PVC is quieter, cleaner, and offers much less resistance to flow or opportunities for disasterous clogs.
That's just a few thoughts for you. Check out the threads in this
link for lots of good info on some general topics. Read it through and I'm sure you'll come up with even more questions! But that's a great way to learn.

Enjoy planning the tank, and get as many details worked out before you fill the tank with water. It's much harder to make changes once the tank is filled.
Nate