Finally! I knew I would only be a matter of time! Welcome to my world Steve
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First off you couldn't be more wrong in saying that chess is just a diversion. Do a google search for "benefits of chess" and you'll see what I'm talking about. The lists of proven ways chess improves the mind are endless! It amazes me that chess isn't taught as a course in public school, although apparently New Brunswick public schools are starting to catch on.
For getting started: I learned from Chessmaster 10th edition, with Josh Waitzkin teaching. I found it far more interactive then learning from a book so it's what I'd recommend.
For chess tactics I'd recommend the chess tactics server:
Chess Tactics Server It will asses you're playing ability and give you problems accordingly. The main drawback to this is that you're supposed to solve the problems in 10 seconds and there's no option to change that.
Another way to practise tactical problems is through chessgames.com daily problems. They have problems ranging from very easy to very difficult. They post one problem each day with the easiest problem on Monday and the most difficult on Sunday.
For good human opponents I use playchess.com because you can use it for free although you have to make a new account about every month. Don't bother checking out yahoo! chess, it doesn't even compare.
Best of luck in the black and white jungle Steve!