Well, a rather "different" time keeping spreadsheet.... Can you convert it... Yes, in a way... Should you? No.
I tried entering one day... first day entered "in" and "out"... worked fine... then entered OT hours.... Well.. First problem is it let me do that. And then you have a rather odd formula that adds time to "payable hours"... 1 became 1.25 ... Now the employees would LOVE this! But I don't think the boss would

Normally, baring any union contracts or other variables unknown to me, OT only comes into play (US law) after 40 hours a week. This in mind the OT should calculate itself.
But thats beside the point.....
I would do it all in Access.... Your Excel files would need to be saved under various names, get VERY lengthy, and hard to read. In Access you would have one DB, all dates, personnel, and any other info packed into a neat little DB. You could look up hours, people, by whatever criteria you need. You can also tie hours to jobs or projects... very handy when calculating job cost.
Look around...Lots of examples on doing time sheets in Access, then give it a try....You will like it a lot more then just using Excel.