I Think I may go for the 20"(Still a huge screen) with
2.16 GHz
2GB RAM
256 Graphic Card
500GB HD
Wireless Keyboard and Mouse

I think the basic Mac software will surfice for now. I only use Photshop for basics (On my PC)anyway I might spash out on Apeture at a later date.

I think Openoffice works well with MAC any thoughts on that software ?
what about iWorks ?

I only do basic stuff with the software I have now anyway. It's mostlly pictures and Internet not to mention Music