Ill let the experts go into more detail into this one for you, but theres several types of filters you can do depending on what you plan on doing now and / or in the long run. For a very simple set up you could get away with maybe two HOB
filters + protein skimmer + 1 1/2 - 2 # of live rock. I know more people perfer to do a sump / refugium, or a wet dry filter, especially if you're planning on getting more sensitive fish or corals later on. Protein skimmer is a must have for any size.
If you have the money, go for the more expensive option.. then no worries about upgrading later
Though if you're brand new, and tight on money, a basic set up will do for now... these people are very helpful and freindly... dont be affriad to ask any questions! Certainly check here before buying anything at the LFS
, especially if you're uncertain. It'll save you a lot!