There are as many ideas about marine filtration as their are hobbyists...  but most long-term successful reef tanks are based on these two main principals:

• Live rock/sand bed (for biological filtration)
• Protein Skimming (for mechanical filtration)

Do you plan on keeping marine fish only or corals as well? 

I would definatly want to put some corals and different things in the tank.  I really don't have a very good Idea of what I want yet, I am just trying to get a picture of what I will need to get to that point.  I plan on going to a couple houses this saturday to get some ideas on what I would like in my tank.  

Kevin,

There are a couple methods of filtration, and most people use a few methods at the same time.  In a reef tank, corals and rock and sand provide an incredible amount of filtration.  But they don't remove large matter, or decaying material nearly as well as a powerfilter, biowheels, fluval system, protein skimmers.... things like that.  Plus don't forget the power of water changes.

I would say that the best advice I can give is to do what you are doing, and visit houses tomorrow.  See what others are using.  In many ways the mechanical filtration is not much different from freshwater systems.  The main difference (in my mind) is the use of living substrate for waste removal.  The usage of deep sand beds, refugia sumps, and similar items are the additional filtration set ups in marine tanks.

Just my views

Adam