What is the most efficient method of emailing networked Excel spreadsheets
using Outlook 2003?

I am currently inserting a hyperlink that points to the networked file but,
this doesn't always work. I tried attatching the file from the network but
this only opens in the user's temp folder and would require them to overwrite
the original file on the network with their changes.

I need to be able to pass on the files to be edited by a coworker from the
network.
Is there a better tool for members of a team to access and edit the same
file from the network without duplicating or erasing the work of the previous
member? Please advise.

Sincerely,
Jim