For most courses you are required to have wetsuit, mask, snorkel, fins and a weight belt. Bouyancy compensators, regulators and tanks are usually provided within the course costs. This should be the minimum gear you should have, like i said your time spent diving and money limitations determine what else you should buy - i would go in the order regs, BC, computer then tanks for further purchases (tanks you wont take on vacation with you, but everything else you can). Can you get in any local diving in your area (where do you live?), there might be some members here who might be able to get out with you in the local forum for your area.
Just some starter questions/thoughts.