duration calculator (in minutes)

hey all, I would like help creating a program that would calculate for me the number of minutes between two durations, the format of the cells is for example,

2008/07/03 21:10:01
2008/07/04 1:15:14

and I would like to calculate the duration in minutes, my spreadsheet has times in column A and B and I would like the mins to show up in C, Im finding it difficult because the duration sometimes spans a few days and sometimes a couple mins so it's very tedious sometimes doing it manually,

thanks for your time!