Is the Crucial you have Ballistix or 10th Anniversary stuff? If so you already have some of the nicest chips out there in your ram. If it is the value stuff, then try for a nicer Crucial Kit, which will guarantee you some nice Micron D9 chips. Corsair sort of sucks because they don't make a lot of stuff with Micron D9 chips, which are generally regarded as the best for overclocking. Mushkin PC2-6400 HP2, XP2 and SP2 are also all Micron D9. Patriot has some chance of getting you Micron, but not guaranteed. G-Skill PC2-6400 HZ is made using Micron D9 chips. Something with Micron D9s will give you the best overclocking results, so you really want to try and find some memory based on them.