Well, I take it by a-pacer you mean a-data.
Also, I'd make sure your friend knows a ****load about Memory or has personally owned it before I would take his advice over a LOT of other peoples advice on a computer guru forum.
But, about the Kingston Valueram. Check out the memory section for a thread that flapperhead has. Valueram is always a pretty good deal, but you are taking a big chance of gettin some dud-ram (which happens with a lot of others, also)
I think either selection will be a good choice but the a-data will give you better performance for your needs. (DDR500 vs DDR400)
And from my numerous readings on crucial memory, they are good for stability, but pretty much crap for OCing (correct me if I am wrong)
I'd go either the valueram or a-data
On a final note, if you want to do some serious OCing it would be recommended to get some heatspreaders for the valueram.