basic voltage questions.

Aright I'm a total noob to overclocking.

I've found my most stable settings to be at 160FSB with a 3:4 memory divider with the tightest timings.
In order to run everything perfectly at these settings I have the vCore set at 1.55v and RAM at 2.75v.

My temps are fine. Is it okay to keep everything running at these voltages 24-7? How high is too high for the RAM?

thanks in advance for helping a noob out.

sure, it's ok. many people don't go over 2.7-2.75 on the ram, some go as far as 2.9, others even go over 3 (those who have lots of money )
I'd say 2.8 is ok for ram, just be sure to cool it if it gets hot.