Best memory for moderate OC on Asus P35 MB?

[dmc3106]

Can anyone provide advice for fastest memory configuration in moderate OC on Asus P5K-E/WiFi and C2D E6750?

I am currently running;

'Crucial Ballistix 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory - Retail' in the system but want to upgrade to 4GB (swap out sticks)

Thanks!