For applications of, say, 1-5 users, Access is a great DB platform. As a RAD platform, if you can do the job within its confines, without writing code, it's great. But if you do need to write code, the restrictions of Access's forms model become frustrating very quickly.
If you expect the amount of custom coding that will need to be written is non-trivial, and if you have any programming experience, I would consider a different route. Continue to use Access as the database engine, but forget about its RAD development capabilities. Instead, download one of the free Express editions of Microsoft's Visual Studio, and you'll have a free development environment for VB.Net or C#. They can interact with an Access database just as well as code you write in
These are much more sophisticated (which is the flip side of more complicated
) but in my opinion they offer a much more coherent
experience -- things will make more sense, as opposed to Access's platform, which has evolved into a Frankenstein monster without any real unifying philosophy (making it impossible for me, at least, to intuit how any operation ought to be accomplished).
I have the book that Perry suggested above, and I thought that it's pretty good, at least using it to quickly look up how to do a particular operation.