Excel time-stamps - per row?

My company deals with trucking companies as vendors. We are using an Excel 2007 spreadsheet as a defacto database keyed to each company's unique federally-assigned number. This spreadsheet has each company in a single row, with the columns containing critical info like name, contact, address, etc.

Periodically, a company will change it's info. They move buildings, change phones, change contacts, update their billing info, etc. When this happens, I go in and change what's necessary and all other Excel documents that pull info from that "database" spreadsheet automatically update the next time they're opened. No problem there (thank the Excel gods for v-lookups).

However, since there are two, and soon to be three, different people using, updating, and requiring info from that database, I would like to try and timestamp any changes made to individual company records.

Is there any way to add a column, say on the far right side of all current info, that will automatically time-stamp a change made to any of the cells in that row? I know the file itself gets a time stamp any time it's opened and changed, but with over 1000 companies, that's fairly vague.

With my admittedly intermediate expertise at Excel, I don't see an easy way to do this, but maybe someone out there does...short of telling me to move it all to Access, that is.