I wouldnt worry about the corporate crap, too much stress, I get your point but it wont help you learn maya,

anyways, I think the need for Maya 5 tutes has been gone a while now, but I wouldnt let that be of concern, the principles of Maya remain basically the same as ever, Ive been using maya 6 until just around christmas time when I upgraded to 2k8, theres a few bits to adjust to but nothing drastic.

Maya still has its frustrations LOL, I think just get your head around whats not in 5 and vice versa with 8 and go from there. Again there'll be plenty of help about if you get severly stuck.

cheers
Jay