here's a good place to get info on cactus and succulents:
http://www.succulent-plant.com/home.htmlif you're really interested, join your local cactus & succulent society. i belong to the one near me, and they have monthly meetings, classes, shows, and sales.
i've been collecting and growing them for the past 5 yrs. or so and it's definitely become an obsession.
most do well with very little water, and won't tolerate too much water. there are some amazing flowers, some pollinated by flies, some by moths, etc.
have fun!