[OS X TeX] Left alignment of the section names

[Amar]

I am using Tex Live 2009 on my macbook. I want the section names to be 
left aligned (on the left side of the page). And also instead of having 
the section names like :

1. Introduction

I want them to be like :

1 Introduction

without the dot (period) after the section number. Anyone has any 
suggestions??

Amarnatha S Potturi