“Heroes of Might and Magic V: Tribes of the East”

I have an AthlonXP 2000+, 256*2 DDR2 RAM, ATI Radeon 9600 128 MB, and I play at 1024*768 with half anti-aliasing – everything else is maxed out. On small and medium-sized maps, the computer barely lags, but on large maps, there is some lag, not to mention XXL maps. Question: Will 1 GB (or 2 GB) of RAM help solve the problem?