Whats the easiest way to slaughter a cow?

I recently bought a cow from a farmer for $50, its much cheaper than buying meat from a supermarket or butcher, now the farmer tells me that I have to kill the cow myself before I can take it off the farm.

I am a bit of a crybaby when it comes to blood and guts and such, so I want to do it as easily as possible. The farmer offered me the use of his gun or anything out of his toolshed, but i declined, its just too brutal.

What I was thinking of is gassing the cow from my car exhaust, putting it in a room and suffocating it with carbon monoxide. I have heard its a pleasant way to die, if pleasant is the right word. At least it isnt as bad as anything the farmer is offering.

Are there any other easy ways to kill the cow?

Will the carbon monoxide ruin the meat?
i dont know where you are from, but round these parts $50 bucks a cow is standard, not everyone lives in the usa, try looking at the globe once in a while