Heya Ktoland!
The first thing I would suggest buying is a book called the
The Conscientious Marine Aquarist. You can have the best equipment in the world and kill tons of fish and end up completely frustrated and miserable in the hobby. The first and most important equipment you need to use is your head, grab that book read it, then read it some more. Tons of questions will come up, come ask them here, most of the people are wonderful and very helpful....some will be sarcastic tools, ignore them. What I didn't do before I set my first tank up was plan it out first, which I really should have. I did what you are probably going to do and that is get excited and run buy some stuff to get it going as quick as possible, it's a mistake...but if you do it, don't let it frustrate you if it doesn't work. Just look at the problems that come up, read that book and if you can't find the answers come here and ask them. I would go for as large a tank as you can afford and remember that the actual tank is just the beginning, filtration isn't cheap, and then comes the live rock and so on. What kind of tank do you envision? Agressive or non-agressive fish? fish only or fish with live rock? or are you gonna go for the whole reef thing? Get to thinking about what your goal is, try to make it a simple one, maybe a tank with some non agressive fish and live rock. Go slow and research research research! compared to most on this board I know very little, but that was my 2 cents!
-Steve