there isn't that much of a difference between the two. the main difference is that the fx has a dual channel memory config, versus single channel for the 3400. this doesnt make too much of a difference unless u use workstation apps like 3d modeling programs. i would suggest checking out this link to see the actual difference between the two.http://www.anandtech.com/cpu/showdoc.html?i=1946
, it has a bunch of benchmarks comparing the two. and for the second question, they will continue production of 32 bit processors, as they are keeping the athlon xp for their budget line.