DDR3 vs. DDR2 RAM

i have 2GB Kingston DDR2 667mhz and i am looking for new ram with ddr3 technology. I noticed that the price on DDR3 is higher, but is it faster than DDR2? is there any difference between DDR3 and DDR2 ram?which one is best?

While the difference between DDR2 and DDR3 RAM lies in the doubling of the frequency bus, the DDR3 works by doubling the prefetch data.DDR2 and DDR3 are both memory technologies that attempt to provide computers with high bandwidth memory. DDR3 SDRAM uses 8 internal banks to carry out 8-bit prefetch. As for servers and workstations these new DDR3 will be very good but not for regular pc.

Double Data Rate 3 Synchronous Dynamic Random Access Memory (DDR3 SDRAM) is an improved version of DDR2 SDRAM. From a price/performance DDR3 memory is more expensive than DDR2.The memory used in desktops personal computers has one notch and also uses 240-pins but is keyed so it cannot fit into DDR2 memory slots.

check this thread :
Best Between Ddr2 & Ddr3 Ram?
difference between the frequencies of DDR3 RAM