I have a really stupid fault, I'm sure its me; at least I hope it is me

I've been using Mandrake Linux to run my home network for a good few years now, found it to be rather trouble free; but now I've become a little unstuck.......

Just built myself my dream system, dual everything, but can I get internet sharing to work on my newly downloaded Mandriva 2007 Free edition.

I've tried several different installs/configurations and even tried several hardware configuration from various NIC's to different systems all together. I've never had this problem before???

I've possibly spend the best part of 80hrs on this problem, serious head ache.

I can see several errors/places I may be going wrong, but does anyone know if Mandrake 2007 has any issues with regards to internet sharing.?????????????