Honestly, child porn may be horrible, but I'm of the opinion that efforts should be made to prevent and punish the crime, not limit the distribution of the material.
Yes, yes, allowing distribution encourages the crime, but personally the act of propagating information or media is not, and should not, be a crime in and of iself. Because you have to seperate the act itself, be it child porn, murder or whatever, from the distrubution of materials relating to that subject. For example, I have a serious problem with murder, but I'm willing to bite the bullet and let someone freely distribute pictures of their latest murder victim, if thats the price of ensuring freedom from censorship for other, more important, issues.
I guess its kind of a personal opinion, and there is no "answer", but to me freedom is primary.