Everyone is headed in the right direction here. Dahawthorne's description is exactly, visually, what I think the answer is.
If the Vista laptop is your main PC, and you want the info from that PC to transfer to the AX and then sync to the XP PC, it is as simple as selecting which way you want the data to travel from the ax to the PC in activesync settings for the PC. Obviously your axim is syncing the info off of the vista PC to transfer it to the XP PC you need to set up activesync like this
Right click on the PC name in activesync and select
If you set up activesync like this on the XP PC it will leave all of the info on the axim and transfer it to the PC
HTH