I'm going to assume the '333' refers to KT333 chipset, right? Base your choice on 1/5 divider as the highest you have. For money, you'll want something that can do cas 2 in the 166 - 180mhz range, which would be a 'smart' overclock for that chipset. For stability, you'll want a name-brand stable example of at least DDR333 (PC2700) that can comfortably do 166mhz.