I thought the answer was
Horse
Doesn't seem to match every line though
Scratch that thing,
It's the name of this being!
Not only a furry creature,
But the sweetest of nature!
Horses have sweet natures
Damn horrible intruder,
Get out of my computer!
Trojan horse
Surely ain't emblem of pluck,
At most it may bring luck!
Lucky horse shoe
guess 2
Rabbit
Scratch that thing,
It's the name of this being!
Rabbits scratch, and some are called Scratch
Not only a furry creature,
But the sweetest of nature!
Rabbits are sweet natured
Damn horrible intruder,
Get out of my computer!
"Bunnie" http://en.m.wikipedia.org/wiki/Andrew_Huang
Surely ain't emblem of pluck,
At most it may bring luck!
Rabbits foot