The first one is Cas. Than one of the others is RAS to Cas, than something RAS and the last one is cycle time, all in M. seconds.
The lower it is the better.
Geil do have the 1.5-2-2-5 at 400mhz and 2-2-2-5 at 500mhz. And their value is meant to overclock well... (Just so I don't mislead anyone who reads this, if you get the Geil One ram, than you can't put the CAS latency as 1.5, as the memory controller doesn't support it.)
For overclocking, I would look for them in this order: G-skill, Patriot/mushkin and then OCZ.
Value Ram, I have no problems with my Geil value.