there are many things that influence your decision....
1). do you really NEED 2x1gb sticks?
2). does your board support your choice- ie. voltage needs, #of dimm slots, etc....
3). do you want to REALLY OC or just tinker?
4). have other users with your board had good experiences with your choice?
5). what is the multiplier of your cpu, and is it likely that you will have to run a divider on the ram for your "desired" OC. ie.- do not get value ram rated at 6-3-3-2 @ DDR400 if you are going to want 1:1 @ DDR600 to get your OC.
The last question will really help to decide for you. If you have a CPU with a 9x and want to hit 2.7Ghz, your memory will need to run DDR600 or on a divider to be in spec. If your cpu has a 10x, your memory would "only" need to run DDR540- which is far easier than DDR600 and has many more options in ram.
Here is what I did.... I got some stuff that will run DDR600 and realize that I may even have to run a divider if I get a really nice CPU that will take 300+HTT. It does not hurt much to be on a divider.
lastly, will your wallet mind your choice