Hi Hi~ I'm currently following the KDrama, too (on KBS, reached ep 14). I loved it til ep 8. And I love Jang Geun Suk (MuGyul).
When I read the 1st manhwa chapter I found out it's very different that the Kdrama's first ep. So, I believe they're not tied in except in the main plot device: arranged marriage and the deal. ^^ If anyone read the manhwa please enlighten us~