New external hd

WD External Drives External Drives for Mac
1

Hi - I’m thinking I’ll be needing a new external hard drive for my Macbook.  I’m running 10.6.8 and my Macbook is at least 5 years old. 

Any suggestions for my purchase?

2

Do you know the capacity your computer supports? Of any drive I’ll select the Caviar or Scorpio black.