Dual channel basically gives the RAM more bandwidth to the motherboard and so the CPU when two modules are used (2x512mb for instance) (about double) though both the RAM modules and motherboard have to support the feature to work. So it gives a little boost when used.
You'll be doing good with that RAM and its definitely more worthwhile getting 2x of somthing than 1x of that 1gig value.
Here is a bit about it:
Features of DualDDR memory architecture include:
* Highest memory bandwidth: DualDDR combines the power of DDR400 with two independent memory controllers, which yields a staggering 6.4GB per second of memory bandwidth—twice the memory bandwidth of other DDR400 chipsets. Increased memory bandwidth delivers better system and graphics performance, resulting in more overall productivity.
* Lowest latency: Both memory controllers operate concurrently with each other to hide latencies associated with typical chipsets. For example, controller "A" reads or writes to main memory while controller "B" prepares for the next access, and vice versa. As important is the second-generation DASP (dynamic adaptive speculative preprocessor), which has been re-architected for improved performance.
* Most stable and flexible memory system: End-users can now populate higher density DIMMs, up to 1GB each, to utilize the entire 3GB memory address map. This large memory map allows more applications, audio and video streams to coexist without conflict.
I hope this helps