32 bit OS is what is limiting your ram. There are a lot of terms in the bios is there anything in particular you were wondering about, as it would take a very long time to list and define all the terms.
You are right, main one that I am interested in "Ganged" or "Unganged Memory". MY CPU is a three core (started life as a 4 core but 4th did not come up) so it seems to me that two sticks of 4 Gig DDR2 memory would not be best running in "unganged" mode, but I am not sure. - Thanks