People will use my spreadsheet at work on a network
drive. If someone uses the sheet can I log their windows
xp pro username and the date and time in a hidden sheet
for me to review?

Maybe a step further is to log all keystrokes A-Z and 0-9
for any entrys in the past 48 hours! This would
eliminate the file from going huge as there would only
ever be in 48 hours around 1000 words or numbers ever
entered.

Hope you can give me some help on this one :-

Regards and thanks in advance