SuperTalent 2GB 1GHz DDR2 kit
 

We had a play, but we weren't able to get the memory to clock up to 1067MHz, even with a little extra voltage. The memory is rated to 1000MHz, and doesn't appear to want to go any further. It's possible to tighten the timings a little if you want the memory to stay at 800MHz, but you'll get more mileage out of extra speed if your processor can take it. The overclock you can get will also be very reliant on the individual modules.