Access hasn't been (and is unlikely to be) ported to OS X. There are a few similar programs, like OOo's Base and Apple's FileMaker. Also a lot of engineering apps don't have OS X ports, so you'll have to go to the computer lab or library to use them. There are a couple SQL servers for OS X; VB scripting isn't going to work outside of Office; java works fine.
The iBooks and 12" PowerBook are dated, to say the least. Apple is currently in the process of transitioning from PowerPC to Intel chips, and a new low-end laptop (probably 13" widescreen) is expected in April. I advise waiting for it to be released.
If you still want to go with the PowerPC model, the PowerBook has DVI, a metal case, and native screen spanning support, while the iBook has better wifi range and battery life.