Memory Timing Question

[JLCollier2005]

It's been years since I built my own computer/upgraded ram, and I was just wondering what is considered good timing for ram? and how do the numbers work? My current ram is 6-6-6-18. I was looking on newegg and saw 4gigs of corsair (heat-sink, 5-5-5-18) and 4gigs OCZ (heat-sink, 7-7-7-24) for about the same price. Mine is right in between so this confused me even more! Any help would be great!!!

 

[Blain]

RAM is relatively cheap,
Timings mean almost nothing these days,
DDR2 and DDR3 aren't interchangeable, buy what your MB supports,
Stick with DDR2 @ 1.8-1.9v or DDR3 @ 1.5v