I have winxp loaded in two partitions and officexp in a third. Is it possible to open officexp in either winxp os?

   If I understand you correctly, it does not matter on which partition you have OfficeXP or on which partition Windows is.  It only matters whether you have installed OfficeXP on the Windows that is running.  If you have installed OfficeXP on the Windows that is running, it will open.  If you haven't, it won't.