You can do time adding up in Excel, as follows:-
1. Open an Excel spreadsheet.
2. Format the row in time format (hh:mm if just minutes, hh:mm:ss if times include seconds).
3. Type your times into the boxes in the column.
4. Click on the first empty box at the end of the column.
5. Click the 'total' button (the Sigma sign). A formula will appear.
6. Hit tab.
As if by magic the total will appear. (It's how I do my timesheets).
Hope this helps (if you have any questions please PM me).
Edited because I forgot. If you are using XP the total will omit whole days (e.g. if the total time should be 27:40:15 it will show as 3:40:15). Annoying and I haven't figured a way round that yet but should be fairly obvious.