Dual channel is a technology to help reduce bottlenecks, between the RAM and processor. And the technology works by increasing the amount of memory bandwidth available. Basically it's like adding another lane to a highway to reduce traffic, and also to increase the flow of traffic.
You're going to buy two of that, for $200+? The performance, is no different from the cheaper RAM, that I suggested at newegg.com........Heres a cheaper one that will work just as well:
Newegg.com - OCZ Value Series 1GB 200-Pin DDR SO-DIMM DDR 400 (PC 3200) Notebook Memory - Retail