I'm not sure why this is suprising. I could have guess the P5 was going to be 64-bit. If your signing up for a future Windows Beta then it's probably nice for Microsoft to know what processor you'll be using on it.
i think they could of ment the pXE , has the 4 has finally been dropped from the labeling
or it could possibly just be a new up-coming line , given that the pxe is a dual core line , and after seeing the 4800+ dual core amd reviews , i think this is likey to be dual core , thou you won't see any improvements till software publishers release updates/patches to enable their app to be multi-threaded , while on the subject of processors aswell , far-cry got a 64bit code patch , it's a start as you can probably expect to see more patches/updates for games and apps being released to help make dual core worth looking at as a upgrade path in the near future , and accordingly to some mag , longhorn is recomending for sys requirments a dual core cpu , chunky hdd space (buy todays os standards atleast) and alot of memory (i think thou it only concerns those who want to use the new longhorn style desktop) they also obviously mensioned a while back that you would need a good gfx card (64mb and up) but now they say a geforce6 and up for recomended