OK I thought that's what you meant.   I'm running a 64 bit dual core now.  But I am using 32 bit Windows.   Dual core basically doubles the speed of any multithreaded app (eg UF, PS, and other programs we like to use).  I went from an Athlon 3100 (1 core, 1.8 ghz 256cache) to the 4200 (2 core, 2.2 ghz, 512 cache) and my render times are 2-3 times faster.   Of course I had to get a new motherboard.