When I upgraded to CS4 from CS3, I also received some free offers from Adobe, one of which was a 31 day trial of on-line training from
Lynda.com.
I managed to use 80% of my monthly allowance, spending 3 to 4 hours each day watching these tutorials. You have to watch them on-line in real time, as there is no downloading capability.
I often found that in addition to the learning topic I had selected, as the speaker demonstrated the techniques and procedures, I learned just as much about general functionality, workflow and CS capabilities that I would probably have not stumbled on in isolation, just learning from books at home.
I suspect if you have had formal training on CS2 or CS3, these tutorials may not be as useful as they were to me, having had no formal or class room training previously.
Cheers
Dennis