Take buhsman's advice, look at plcs.net
There is a link from there to industrialtext.com
They sell a big fat book BUT you can download certain extracts from the BFB for free! The one I found most helpful is entitled 'Introduction to PLC Programming and Implementation - from Relay Logic to PLC...
Like some of the others, I got my first copy of LM90 from the VersaPro demo CDROM.
Although everyone 'slags off' the old DOS stuff, this LM90 is a breath of fresh air after battling with STEP5 (the Siemens offering for the S5 range)
If your boss is not averse to playing around with auctions tell...