I always get in trouble in these threads, so I'm going to let others give
you the actual recommendations. I use SolidWorks for work (I'm an
engineer), but I couldn't afford to buy it on my own, and I don't use it for
woodworking projects. I use pencil and paper for woodworking, but then I
can draw (I was trained before CAD became standard), and I don't do
extensive woodworking. Drawing isn't everyone's strong suit, but then again
neither is mousing around, so my advice is to experiment, listen carefully
to the recommendations, and use what is comfortable *for you*.

As a programmer who worked on CAD/CAE/CAM systems, I find a lot of mindsets
apply and therefore a lot of tools exist that focus on each mindset.
There's a way of thinking that gets a couple of key views drawn in 2D and
then extends that to 3D. If you're going to design a chest of drawers, or
some shelves, you're probably thinking of how it's going to look from the
front. So you'd work that view first and then think about depth later, with
joinery and other things falling into place as necessary. Conversely
another mindset tells you that it's a 3D world and so the longer you put off
3D design, the sadder you're going to be in the long run. (That's the
paradigm I work in.) Unfortunately it's not the way a lot of people seem to
think naturally, so it requires you to wrap your mind around the problem.

"What CAD program should I use?" is a lot like, "What kind of car should I
buy?"

The first question you have to ask is, "Why CAD?" There are a lot of
potential answers: lack of manual drawing skills, need for polished
presentation, production efficiency, time savings, skill acquisition, etc.
But seriously you need to consider whether pencil and paper will work for
you.

Another good question is, "If I *had* to design this on a whiteboard, how
would I draw it?" If you draw views in cardinal directions first, consider
the AutoCAD-type systems. If you draw a perspective or isometric view
first, consider the SolidWorks-type systems.

And the big question, which you've already answered, is, "How much can I
spend on this?" CAD programs run the gamut from the basic digital paper and
basic straight line, all the way up to systems like CATIA that you can use
to design your own stealth bomber. As someone said, a good CAD system may
not make up in the long run for a good band saw.

Good luck, and be sure to tell us what you discover.

--Jay