random quick question

my computer (sony vaio, pretty much right off the shelf) has 4 RAM module slots. its a 2 + 2 looking configuration, but the modules that came built into the comp are in one of each of the 2 pairs of slots. my quick question is if say i pulled one out and filled one pair of slots, would it make any difference at all? id guess not but i figured id ask the pros....

the only difference I can think of is if they're running dual channel now, they might not run it if you stick them next to each other