Stuart,
I can't reproduce your problem.
1st I tried it on my Novell Netware server. When opening the file and looking at properties from inside Excel it showed the modification date and time as the current date and time. When I close the file (without saving) and check properties by right clicking on the file name, the modified date and time are back at the original date and time.
I then copied the file to the SME7 server, checked the properties by right clicking the file and it looked just like on the Netware server. I then opened the file and it was the same as Netware with the modified date and time set to the current date and time. I then closed the file without saving changes and the date and time was set back to the original just as I would expect.
This excel file was created with office 2k by another user. I opened and closed it with office 2003 from a different workstation.
Royce