Join
www.ultimatereef.net and have a look at some of the setups on there. I got the best advice from that site and you can pick up some decent stuff in their classified section, some real bargains.
As for what you'll need, that depends on what you want to keep in the way of livestock.
You'll definitely need a skimmer, use the Berlin method and go for water movement and live rock so you'll need powerheads and obviously the rock. decent lighting (corals require stronger lighting T5s or Halides) and heaters.
Steer clear of anything that will act as a dirt trap like trickle filters and media sponges as they will affect your levels. Get yourself a testing kit for ammonia, nitrates, nitrites etc. You'll need something to test salinity and of course you'll need the salt.
Water needs to be RO, you can either purchase an RO unit to plumb into your house (easily done) or you can buy RO water from most local fish stockists.
That's pretty much the basics, you can go in for coolers, UV filters, wave makers etc depending on how far you want to go into it. Also a lot of people have a sump (I didn't) but it does make life a lot easier and the water levels more stable.
Be prepared for a lot of work and a lot of expense. Marine tanks tend to turn you into your electric companies best mate.
My tank when it was up and running. I've just shut it down recently unfortunately.