bad ram use loose timing (i.e. 3-3-3-7), which can't be loosened any more, causing limited/no oc
also, bad ram uses cheap black chips on ram, which makes ocing impossible/hard
on the other hand, good ram uses tight timings (i.e. 2-2-2-5, which can be loosed to something like 2.5-3-3-7 for even better ocing)
also, good ram uses good black chips and a good pcb board (that green board the black chips sit on), which makes ocing easy and can reach higher fsb's
edit: you DON't need to oc at all
i have a 3200+ and a 6600gt (3000 is no different from the 3200 in performance, sicne you can't feel it at all) and everything runs smooth with no lag at all
the only lag i ever get in games is the once in a while lag spikes my internet gives me