Are 2x256mb modules equal to 1x256mb module on a dual channel mobo?

[BentValve]

Dumb question: Are 2x256mb modules equal to 1x256mb module on a dual channel mobo? It seems thats how it would be but?

Also what is a better arangement for a dual channel mobo 2x256mb + 1x512mb or 2x512mb ...or just two fast 256mb modules?

 

[Budman]

Dual channel mobo with 2 x 256 megs will run in Dual mode and have 512megs total.

Dual channel mobo with 1 x 512 meg stick will run in single ddr mode & will be 512 megs total.

So in a Dual ddr board it's better to have 2 X 256 megs to enable Dual ddr mode,using 1 stick will default to single ddr mode.