Seperate First, Middle and Last name to seperate columns

Hi!

i use MS Office 2007

I have a column A containing FULL NAMES
(which consists of :
1. First name OR
2. First Name and Last Name OR
3. First Name, Middle and Last Name)

I would be grateful if i could get the results in separate columns (i.e. column B= First Names; column C= Middle [return N/A - if MIDDLE not present]; column D= Last Name)

appreciate your early reply