Well, I think there'd be a lot of agreement here that the best way to review and drill the tables is with
TableTutor from ScubaToys. It has table formats from all the major agencies, and lets you run single-dive, multiple-dive, and missing surface interval problems.
And it's free to ScubaBoard members... yeah, sound like a marketing thing; and why not? ScubaToys have done a lot to earn customer loyalty.
You download it, then run it. It gives you a "Register Your Software" screen with a unique shareware number. Don't register on-line; you'd have to pay either $14.95 or $19.95. Rather, e-mail or PM ScubaToys, telling them you're a ScubaBoard member and with the shareware number; and they'll send you the matching unlock code for free.
(I just re-formatted my hard drive, and need a new unlock code.)
The PADI Wheel? That will be tougher. It comes with what I thought was a very complicated manual.
My opinion? While I think it's necessary to understand tables, there's too much room for human error with The Wheel when doing multi-level dives... I think the cost of a basic computer is well worth it in that case.
Others, I'm sure, will disagree with me.
--Marek