I love these urban legends.
“My computer was making a hissing sound. Just look what i found when i opened my PC..a snake! Look, heres some pictures to prove it!…”
Taken from urbanlegends.about.com:
Computer CPUs generate heat and reptiles like warm places to hide, so it’s not implausible, given the opportunity and a big enough opening to squeeze through, that a wayward snake would take refuge in the housing of a PC.
This comparative richness of narrative detail, the fact that more than one variant of the story exists and the up-front insistence that it’s absolutely true are all hallmarks of an urban legend, suggesting that the forwarded text may well not provide a true account of what’s going on in the photos.