Read this article to find out if you should buy DDR2. http://www.tomshardware.com/firstlook/20040716/
Ballistix is just the name of Curcials Proformance memory. Curucial/Ballistix is a name brand, in fact they are the lagest producers of Dram in the united states. Top 3 manufacturers in the world are: Samsung, hynix, and Micron technology. (micron owns crucial)
Micron is the first memory semiconductor manufacturer to gain Intel validation across all densities, speeds, and configurations of DDR2 SDRAM components and modules.
Kingston does not produce memory it buys RAM/die (those black squares on the ram module) from actual Dram manufacurers and puts it on a module, then sells the module with kingston label. so you dont know if your getting some ram they bought from a small company no one has heard of or if its good quality ram from a company like micron or samsung. i would not reccomend kingston if your looking for "high" performance ram.