Pick the ram according to the multiplier on your 939...
If its a 3000+ winnie which has a 9X multi, you want something with TCCD. I prefer G.Skill PC 4400LE for this.. Hits 300 with low volta, 2.5,4,4 timings. Some can even do 2.5,3,3 @ 300.
If you have a 3200+ which has a 10X multi, go for the new OCZ GOld PC3200, which is basically BH-5.. $173 at the egg.. good stuff. Does 260 @ 2.2.2.8 @ 3.4v.