thanks for all the advice so far.
managed to get them to hold my place until the next semester starts in sep 2008. so guess i'll have some time to think it through.
the opportunity cost is there for sure, but it's something that i really wanna do. ideally, i'd like to get my boss to allow me to go for 10 months on no pay leave... but dunno how to broach the subject esp. when i'm still new...
well anyway will start worrying about it come mid-2008. heh :)