depends on who you talk to. dual channel adds like 7-12 percent improvement in bandwidth.not great, but not bad. 256m chips also SEEM to overclock better, imop, but 2 chips are usually harder to overclock than one. now a single 512 stick has a downside, in a sense, that is it may not clock as well as a single 256 chip, but to counter that you only have one chip, which is generally more stable than 2. now mind you, when i say stability i mean at high overclocks, not runnin in spec. so for me the answer would be " how much ram do i want to end up with" if its 512m then id get 2x256, if it were a gig id get 1x512 now adn then try to find a exact match for it later to=1gig. as for the whole dual channel thing, i dunno, to me its not a big enough factor to really come into play on my decision. if i can end up with 2 sticks, then wohoo!! i get a slight bandwidth increase. if i only end up with one, wohoo!! ill probably be able to hit a slightly higher fsb.