Mechanical Man in Tales of Transhumanism

I've always been interested in cybernetics. I think it stems from an early childhood being spent with my older brother watching 80's sci-fi/horror/action movies that usually featured cyborgs and robots and other cyberpunk themes. Twenty-plus years later and I still haven't shaken that fascination; if I could have a limb removed and replaced with a cybernetic version, I would. This, of course, should come as no surprise at all, considering that I am a transhumanist. However, technology isn't quite there yet, although science is definitely catching up to fiction even as we speak.

It's the ultimate form of body modification; replacing one's organs and limbs with cybernetic and/or mechanical devices. The question, as always, is when would you stop being human? You have a fake heart, fake lungs, your limbs are replaced with cybernetic ones, your brain is replaced with a super-computer - when would you stop being merely enhanced? When would you cease to be human? Where's the line?

Doesn't matter to me. I've lived half my life in the fantastic realms of science fiction for many years now. Crossing the line wouldn't really affect me now.

Catch up, science.