Depending on the draw on the machin typically anything between 0.2 amps to 1.5amps with an average of around 0.5 amps.

You will also need a data pipe to your home if you ware to get any good speed out of the connection. 8MBPS broadband should be fine if its not a high traffic site but many ADSL providers will not allow you to use the connection for hosting.

I can however guarantee you that in the long term hosting with a web host will be cheaper than doing it yourself.

PS: Does it have to be godaddy - you could do so much better.