First you should get a water report from your local DPU/water source. Some folks are downright blessed with their water.
Not sure about Charlotte, N.C. tap water, but I'm going to say you're moderately alkaline to soft.
Depending on the chemistry of your water, you may not even need a filter! However, I would recommend getting
http://www.protectionforliving.com/w...ters.php?cat=9 (CARBON FILTER, BOTTOM OF PAGE).
Carbon filters filter out ammonides + chlorides, which contribute negatively to taste + smell in water as well as contribute clarity.
I usually attach mine to a hose, but I'm planning on installing it sometime into the actual piping in the basement. Your beers will be delicious!
If you wanna go gung ho, get a Reverse Osmosis filter and build your water table from there!