that's wierd, i did teh exact same thing to the exact same board.....are you using the big passive zalman heatsink deal ?
anyway, if i remember correctly, the pins go through to the bottom of the mobo. you just have to squeeze the ends of the pins together from the bottom w/ some needle nose pliers or something. Then just pull the pin out from the front while squeezing the ends together from the back. let us know how it works.