If youre doing 2D, then I would just get a book. AutoCAD is very simple to use and pretty intuitive.
I don't have a lot of experience with 3D AutoCAD. I use Solidworks on rare occassions for 3D work. 3D is a little tougher to wrap your brain around, (at least for me). A class might not be a bad idea if you're going that route.
BTW I hated AutoCAD 2010. I used it for a few weeks and tried to like it. But it was so clunky, slow, and didn't have any new features, (at least that I could have used), and the ribbon thing made it impossible to find things. I switched back to my old copy of 13. For the simple drawings I do, its more than enough
R13? Yuck!
I used R14 for years. Started on R2.62 then went to R10, then R12, then R14, when the company went to LT98, I kept using R14 (because I used LISP). I stuck with R14 while the company went through the LT series.
I changed jobs about a year and a half ago. They gave me 2009. We are now migrating to 2010.
I admit that R12 or R14 will do everything that we need it for, but they seem to want to keep up to date on software.
2009/2010 are just the way Autocad is moving forward. I didn't like the screen icons or menu system, but it is progress. (and licenses are not backward compatible)
It took me maybe a week to get used to and productive with 2009.
I would suggest (like others have suggested) to find a live person to help you do what you need. It would be far more beneficial than a book. Books are good (and I have several), but you can't beat the interaction between a live person.
If you don't have any people at work, I would suggest taking a class.
Good luck.