when i fix two unequal sized rams in the pci slots will it work..?

if i fix a 128 mb ram in one slot and a 256 mb in another slot can the processor work efficiently?can i take my ram memory as 384 mb then?please guide me in this or else tell me the website where i can get all the required information which would best suite to my [...] http://bit.ly/pOXXcB