Regular expression to capitalize first letter of words in sentence

[Shlomit Afgin]

Hi  

I need to write regular expression that will capitalize the first letter of 
each word in the string.  
Word should be word that her length is greater or equal to 3 letters  exclude 
the words 'and' and 'the'. 

I tried: 
$string = lc($string); 
$string =~ s/\b(\w{3,}[(^the|^and)])\b/ucfirst($1)/ge; 
but it not working so well. 

Any ideas? 
Shlomit.