which of the two are better performance wise? Does it take a hit moving out to 4 sticks? I think the price is slightly better with the 4x512. It's definately better than trying to get 2 sticks of low latency 1g. Thanks for all constructive replies.
More about4x512 latency
If you go with 4 steps, depending on your motheboard design, you may increase command rate latency from 1T to 2T.
i'd go with the 2x1 unless your planning on overclocking etc etc, as this way in a few months you can put an extra 1-2 gb in for a performance boost.