I'd like to also add that the problem with using Reports/ whole page layouts, rather than portals is that I want to have 2 separate portals on the same page. I can do that with portals, just arrange them. I want specific fields popping out half way down the page, which I couldn't do if I had to use the whole page/layout for one type of calculation. It seems that I cannot do that if its a Report.
If I knew a way I could just get the same fields to recognise all the values in the portal above it, and for another portal, only recognise those, it would work great!
look at Summary fields - should work nicely,