Does it Matter?

Voting has always been an obsession with me.  I have not missed an election since I turned 18.  I frequently bore people with political discussions. 
Lately though, I have been wondering if it is worth it.  It seems that no matter who is elected, nothing ever changes.  Part of that is the appearance that our two major political parties are in fact the same. 
Neither wants real change. Both serve the corporate masters that truly control this country.  You know the Multi-National Corporations that control the world economy.   These corporations exist sole to enrich themselves and ensure their own power.  They consider people nothing more that a commodity to be used for what ever purpose they want.
So why bother to vote?  If you are an Obama supporter, he has already been co-opted by the international corporate interests.  Romney is a product of the corporate world.  No other candidate has even a remote chance of getting elected.  The other parties do not have the resources to mount an effective national campaign. 
So Why Vote?