On SpeedFan go to the charts tab and put a check on the top items there. That should track both cpu temps. On a single cpu board the first two are applied to the cpu itself with the third for the board. The temps are seemingly contradictory while still being within the normal operating range.
One thing to note about running XP with dual cpu or dual cored cpus is a special fix for systems seeing performance problems that may help somewhat here since it was originally intended for multi processor boards. You can read over the MS artticle seen at
http://support.microsoft.com/?id=896256