Darren:
I am sure you meant to use exclamation marks for the field delimiters with the Python Parser and not brackets, which are used with the VB Parser. So if the field is called "Name", the expression should instead be:
!Name!.title()
Capitalization will happen only for the first character at the beginning of the field and for the first alpha character that follows any white space, numbers, punctuation or special characters. So you have to check for things like numbered streets which will appear as "1St Street" to make it "1st Street". Also, no alpha characters of a word other than the first one will be capitalized, so you have to check for things like Scottish last names beginning with Mc to change "Mcdonald" to "McDonald". Also it capitalizes all words, including small words that normally are not capitalized in book titles like "a", "an", and "the".