Finally found somewhere on the Apple website that explains what a Mac OSX Tiger user should do to upgrade his machine. The latest Snow Leopard version of the Mac operating system is getting so much attention on their site that it's eclipsing everything else.
Here's an image with the link and information:
The link to the Mac Box Set is here: http://store.apple.com/us/product/MC209Z/A
Basically you're looking at an "affordable" $169 upgrade if you're moving from Tiger to Snow Leopard. I haven't been able to find any links which allow one to move from Tiger to Leopard more affordably and thus allow one to take advantage of the $39 upgrade from Leopard to Sno.