Hey, I'm a newer diver too and been looking into all of the local options as I reside not too far from the Mouse. There is a lake used for Certification that is not far from Disney at all called Lake Denton . . . the obvious downside to this is that it is a lake in FL and aside from the occaisional bluegill and softshell turtle there isn't much to see, 30' max. I've heard Daytona (about a 1.25 hour drive from Disney) has some diving if you wanted to avoid the southern drive to Jupiter, dunno about how deep it usually is but you'd have more to look at. Also, this may be a stretch but Venice Beach would probably be a 1.5 - 2 hour drive from Disney on the gulf side . . . big area for shark tooth and fossil hunting, I just went for my first time this past Monday and while I didn't find anything, I had an absolute blast. . . saw some real crazy looking fish and it was a very comfortable dive (max 19'), they have a couple charter boats in the area that seem to always be productive and even reasonably priced. I've also heard that Bradenton (Tampa Area, closer than Venice Beach) has some good dives that aren't that deep.
Also, I'm trying to get all the dives logged I can. . . let me know if you need a buddy. . . I used to work for the Mouse as a travel agent (I've booked the living seas dive thing a few times for vacationers, but wasn't diving at the time so never looked much into it) so maybe I could even help with some general Orlando vacationing/disney vacation type questions you may have.
Good luck!