I do have very mixed feelings about her, poor snake. This chapter is echoed quite a bit in some unposted bits of LC -- it always strikes me that the snakes Tom uses aren't really at fault, they're just doing what they're told. I don't really like that JKR makes them inherently evil.

And I feel bad that Harry could kill her, an innocent, but not Voldemort -- but then again, if I were really against killing the innocent animals for our own aims, I wouldn't eat meat. :D