Floyd,
Yes PC4400 memory is in theory supported, but the question I have found is whether it will run succesfully at 1T command rate.
I have just sent back 2Gb of TWINX4400PRO from Corsair, as I couldn't get this to run past 255Mhz at 1T command rate, despite having read many test reports that showed it OK upto 287Mhz.
Corsair argue that this memory isn't spec'd at 1T past 250Mhz and that teh command rate is as much to do with CPU/MB as the memory modules, but I personally think it stinks that all "test" modules received by reviewers are fine at 1T and mine aren't.
I am still looking for 2Gb kits that are "guaranteed" to reach 275Mhz, but no luck so far.
The A8N32 will reach FSB's of at least 300, so DDR550 is no problem and even DDR600 should be reachable (provided your CPU is upto it).
Ridesy