I like a 2 1/2 inch knife for the guttin' part. A small knife is much easier to get to the windpipe, and easier when trimming the connective tissue. I use a larger knife for butchering.
PS, don't buy that BS about drinkin' the blood (but do eat the liver if that floats yer boat.) Go slow and try not to pop anything with contents.
http://youtube.com/watch?v=uqm1DA2nyvw