Question about downloading a song?

I have Windows Media Player on my laptop and I keep many of my
favorite songs on it, but I've only ever put songs on it via my
CD's... and there is one song that I really want but I don't have it
on any CD's. The song is called 'Field of Innocence' by Evanescence.

I'm wary about downloading ANYTHING off of the internet, and since I
only want the one song I don't want to pay for an entire month or
something like that... is there a safe legal site that I can download
the song from?