[LemonyBrainAid]

If you right click and go properties on the song in question, you can change the ID3V2 tag.

A window should pop up with two tabs - "General" and "Summary". click on the "Summary" one and then click advanced.

There should be a little dialog saying "Music" and then "Album Title" and "Artist". To change the artist name - click on the blank space right of the "Artist" text. Type in the artist name(s) and click apply..

And you're done.