I OC my E4400 to 1.8ghz - 3ghz, multiplier of 6-10 with Speedstep.
 
My FSB for CPU is 300 therefore the OC results above.
 
Question is my ram, should I stay with the 1:1 ratio 300(600), or should I OC the ram to say 400(800) or higher.  Will I see any improvements or as a review I read before that the best results is usually 1:1 ratio and any others there won't be any huge improvements.

Only some memory benchmarks will show any differences between those memory speeds and in real life operations you wont notice a thing. And I've been informed that the 1:1 ratio is more stable aswell, so easier overclocking..