I have to pop in here.
Whilst AC3D is not as well known as 3D Studio, AC3D
is very widely used see:
www.inivis.com/where.html
As well as many sites using it (not all are listed above), we have thousands of registered users.
One of the powers of AC3D is that it doesn't really need a training course. Schools we work with are disillusioned by other software which is over-complicated and hard to use AND requires training. They find AC3D a breath of fresh air and students can produce results so much quicker.
We have a training pack and sample files which schools use to get started. It takes you though the basics. After that, the manual really is quite useful, as is this forum.
If you could like a copy of the training pack send me a private message on here, making sure you let me know your email address.
Andy