Hi Che,
To start with you'll need a large board and a small sail. These can be gotten quite cheaply if you're prepared to put up with something that looks a bit old and tatty (I paid $200 for a complete setup), or you can go the whole hog and get something like a Starboard "GO" or "Start" with a beginners sail brand new for something probably approaching $2000. You want something big, floaty and stable, probably around 160 or higher litres.
I would also recommend that you get at least one lesson, this can really help you to know how to rig, how to get going, and turn around when you're far enough out.
You will probably outgrow this setup in under 6 months, so be very aware that this is not your final board, and you won't be able to jump it or ride it in the surf. Coming from a surfing background you're at a bit of an advantage here, it might take you around 2 months if you're really talented.
Once you can uphaul, tack, gybe, go upwind and downwind, then it's time to start with the fun stuff -- a real rig. Onshore waveriding needs a bit more volume than offshore stuff, and the general rule of thumb is your weight + 20 kg's (so you'd get a 95 litre or thereabouts board). The transition to such a small board will take some getting used to, so be prepared to have some trouble adjusting.
Again, you won't be able to go out in the waves until you can waterstart. This is a skill that is difficult to learn if you don't have someone telling you what you're doing wrong, and your surfing background won't help you. The smaller board will make this slightly easier, but it's still a bugger.
Once you can waterstart, then you're ready to go into the waves -- pick a day that has low swell, and especially small shorebreak, yes you're going to look like a gumby the first few times trying to get out into the waves, but once you get the hang of it you'll be addicted!
Good luck, this forum is an awesome resource, many opinions on here so take everything with a grain of salt