Tips on where to start with Asterisk?

My 1st post folks. I am a Windows admin & user, no LINUX background. Also a 20 year traditional PBX and fairly large scale VOIP admin. We have multiple sites on Nortel CSE1000 & BCM50/ 200/ 400. Wanting to get feet wet around Asterisk and have a simple project to test with. Where would you advise I start? Should I start by getting some pilot time with LINUX first? Thanks in advance for what is likely obvious.

Learn something about Linux will be useful (in general too), to start know Asterisk read this mine old post, where there is a link about a good free book about Asterisk: forums.digium.com/viewtopic.php?t=63610 .

Cheers.

Marco Bruni