Because I'm Stupid Another Ver.
The title track is 내 머리가 나빠서 - 김현중 but I'm not sure if it is a Hyun Joong voice .
cuz i think it's not similar with the one that i've heard from the series.
Try this~~
http://www.megaupload.com/?d=3JEFY2HU
http://www.mediafire.com/download.php?lwzjemgqkzn