Do i need an extra RAM?

Hello,
My computer currently has 2GB DDR2 RAM. I was thinking to upgrade it. I mean to buy another DDR2 RAM of 2 GB, so that my computer works even faster. I've had no problems with the speed till now, but since DDR3 RAM has come, i thought i would not get DDR2 RAM later.
CURRENT RAM is :
DIMM1: 2 GB DDR2-800 DDR2 SDRAM (6-6-6-18 @ 400 MHz) (5-5-5-15 @ 333 MHz) (4-4-4-12 @ 266 MHz)
Please suggest me a new RAM, also tell me whether i require a new RAM.


These are the supported RAM Types:
Supported Memory Types DDR2-400 SDRAM, DDR2-533 SDRAM, DDR2-667 SDRAM, DDR2-800 SDRAM, DDR2-1066 SDRAM, DDR3-800 SDRAM, DDR3-1066 SDRAMSource: Application