Yes. The 667 will run at 533. You should only pair memory with memory of the same speed, cas, timings and voltage.
Thanks for your prompt reply. As I have already purchased the 667 DDR2 RAM and using it along with 533 one. I would need to buy another 667 or 533 so that both the RAM's are having the same speed.
Would it be wise to invest in buying a new one or can I run the current configuration with only the 667 RAM working as a 533 one. (which I can live with). I am only concerned about any damage this setup might cause. Please advice.