Excel - put login times into neat hours

I have this info in an excel spreadsheet ..representing the amount of time spent logged in to a computer..

logins  time of day    amount of time logged in (h:mm)------  -----------    -------------------------------login      03:21        logout     05:03       1:42login      05:47    logout     06:26       0:39

And i want to turn it into this ..

time of day     amount of time logged in (mins)-------------   -------------------------------03:00 - 04:00    3904:00 - 05:00    6005:00 - 06:00    1606:00 - 07:00    26

It seems very complicated and I'm getting tied up in knots with excel formulas .. if anyone knows a formula that would be great!