Rather than E4300 or 6300, I think you should go for the newer E6420... Regarding best motherboard, plz confirm if you will need good onboard gfx or not (which will depend on whether you are into gaming, etc and whether you are purchasing separate gfx card) because that will affect what you can get in the given budget...
I am also thinking of upgrading my system to Intel Core 2 Duo E6600. Already have Nvidia 7600 GT GPU.
Please suggest a good motherboard (overclocking support) for Below Rs.9000 range.
Also, is DDR2 800 2 GB stick available in the Indian market? If so what is the pricing?