i use nx70v whit a memorystick duo adaptor to memorystik pro duo of 2gb and work fine,
msx-m2gn
high speed
2gb magic gate
80mbp/s
(designed for psp meybe)
the model for 4gb cost 10 uss more but not have in the moment to test
i compare the memory of 4gb (the pack) whit the memory of 2gb and not see tecnicals diferences... , only capacity..
not buy the mem of 4gb , but a person buy after me XD.
but i think work...
(previus installed in palm the patch of memorystick pro) MSPRONX_ENUS.PRC
to expand to memory stick from 128mb or more. (i install it in mi memory of 64mb)
if not have instaled these sony patch , see a ? over icon of mem..
wen test the memorystick pro duo, first time dont see nothigs signal
onli the / over icon , (show it wen not have nothing conected)
, but , the memory dont insert correcltly in adapter, i make a little force and , make a "clik" and i test and work

if not make a sound or ? signus over mem icon, is bad put in adapter...
in a mem of 2g i copy a divx movie in dvdrip of 700mb and see it fine

whit tcmp, in the other memory of 512 i need convert to little avi (100mb) to see :P
sure have a little hangs , of divx , according to the compression of the film
whit mp3 work fine, i use to copy a usb mem reader.. adaptor..(all in one chinese) :P
the msfile, hang 70% wen copy mp3s... to palm.., not is recomended to copi using base and usb cable of palm,
directly work perfect..
well , now i have problems whit mi batery , wen solve it , meybe buy a memory of 4gb to test

.
good luck ;P