Memory Question- Corsair memory.

I have an A8N32-SLI motherboard running a dual 4500+ CPU, with two 1GB matched sticks of Corsair TwinX2048-3500LL memory that came with the motherboard. My understanding is that with the dual core I effectively only have 1BG for each core, and if only 1 core is active for FSX, then I'm really only using 1GB.With some early reports that having more than 1GB makes a noticeable difference with FSX performance, I'm looking at my on-line vendor for another pair of the same memory, but that part # isn't active any more. I can get (from their Corsair stock) such as :CORSAIR TWINX2048-3200 2GB KIT (1GB x 2) MATCHED PAIR 400MHZ 3-3-3-8 184-PIN DDR DIMM W/HEAT SPREADER (*Limit 2 pcs/customer) or CORSAIR TWINX2048-3200C2 2GB KIT (1GB x 2) MATCHED PAIR 400MHZ CL2 184-PIN DDR DIMM W/HEAT SPREADER both being 2x1GB. Would I be able to use either of these different stick pairs with my current pair and not get into any compatibility issues?Thanks, Bruce.