MAIL MERGE with 2003 vs 2000

I have a job that basically runs a merge remotely by opening the datasource (xls) and running the merge. It runs fine if I run it on a command prompt running Word 2003. Our scheduler, however uses Word 2000 and it seems get an error and lock the file so it can not be used again wihtout a popup. My question is, would a mail merge documnet created in word 2003 (.doc extension) run in mail merge 2000.
thanks,
Bill Hoover