Just thought I'd help out a little with a recomendation or two.
First: I have a 20 gallon tank. Personally, I love it, even though it's small (a 20 gallon is very small for a salt water tank. You should probably get a bigger one then that). What I would recomend is that you DON'T get a big tank to start out (ie. don't get a 125 gallon tank right off the bat).
Here's why:
Starting out with a big tank is a big hastle unless you have a ton of money and can afford 100+ lbs. of LR within the first couple days of your setup. A smaller tank allows you to build more slowly, which means less dough to dish out.
Secound: The number of fish you have in your tank is determined by the tanks size (duh). But just incase you don't know if you have to many or not, here's how you figure it out:
1. Estimate the length (in inches) of each fish in your tank.
2. Add the # of all the fish lengths together.
3. Divide the # of gallons in your tank by 2.
4. If the # of gallons in your tank is larger than the fish lengths, then your set. IF NOT, THEN YOU HAVE A PROBLEM!
Just thought I'd help out.