Pelly... you've been sucked in:
As for the Geil, none of that memory is true DDR400. It's DDR333 that has "been tested" to run at 400MHz. Good luck.
None of Corsair's DDR400 is genuine as of yet. I know. I buy from them regularly. Until they start getting ICs from Winbond, it's the same as the Geil (although probably somewhat more reliable).
As for the Mushkin: PC3200 = 333MHz FSB, Rated 2.5-3-3, 6ns
PC3200 does NOT = 333MHz FSB. PC3200 denotes a 400MHz FSB. That memory is DDR333 (PC2700), again, tested to run at 400MHz (it will only work at 2.5-3-3 (as stated) at 333MHz (also stated).
The Kingmax memory is not yet available at 2.5. It should be available shortly.
So many get sucked in and then wonder why their systems' performance or stability is so poor. The wool is being pulled over their eyes. Just because it says DDR400 doesn't make it DDR400.