Maybe this from Debra Dalgleish's site will help:
http://contextures.com/xlDataVal05.html
deepak wrote:
Dear Expert,
Please let me know how to link a drop-down list in sheet1 of a workbook (say
Sparepart.xls) to a sheet in another workbook (say Estimation.xls).
Thanking you.
with regards
Deepak
--
Dave Peterson