Windows 7: Creating ad-hoc timesheets using the time Excel 2010 is opened/closed

I am looking to create a timesheet so that I can track my work time on various projects and be able to create accurate records using Excel 2010.

I have had a look around online and have found various templates and tutorials, but none of them are quite what I am looking for. (I'm also not entirely sure what I am looking for is possible.)

The work I am doing will be ad-hoc (potentially: a couple of sessions within one 24 hour day; regular daily sessions of varying lengths; 1-2 days inbetween sessions when I do not work on the project) so I do not need the Mon-Fri/Sun layout that most timesheet templates online offer, and as the hours are my own and unscheduled, I do not need the options for overtime/lunch/sick leave etc.

Ideally, the spreadsheet I would like to set up would be able to enter the time automatically when opened and closed, meaning that I would open the excel sheet before working and close it when my session was done. I have little experience with Excel comments and functions, but I think there is a function =NOW or =DATE (or similar) that updates automatically when opened. This is ideal, but it would need to be fixed once updated, so that it didn't update itself again when the file is next opened.

I would also need to be able to convert units in hours to units that can be multiplied by my hourly rate for the final cost. (I have found this tutorial on creating time sheets, but although I followed the instructions carefully, I ended up with a total of 1.36, and not 32.75.)



I'm not sure if this is possible, and (thinking it through) I'm pretty sure it would take some general admin to the form that would be the equivalent of just inputting the time manually, but I thought I would try and find out if there was a solution that met my idea first.

I understand that I am asking a lot, and I hope I have explained what I am looking for clearly enough for you to help me. Any and all suggestions, comments or tutorials/website links etc. are appreciated.

Thank you in advance.