Do you need to know the actual time, like a clock ? If you don't, it is not so hard.
The Arduino crystal has some kind of accuracy, you could use just millis() for time.
The most simple way to get data to the pc, is sending a command via the serial monitor, and the Arduino writes data to the serial monitor which you can safe into a file to be read into a spreadsheet.
Perhaps you might need an extra external EEPROM to store the data.