I just took mine off my new board yesterday. There are tricks like warming it with a hairdryer, freezing it for a few hours, or using acetone or alcohol. (Carefull with acetone, like get a respirator rated for organic vapor, seriously. It could take a while to disolve it off)
Mine just poped off, though. I used my drivers license (plastic laminated) to cover the board, you could try a credit card though.
Put the pci cards toward you and go for the right hand corner. Slide the middle of the short end of the dl under the right hand corner of the sink but over the green pcb directly under the sink. Rest the other short end of the dl on the first dimm slot. Take a small screwdriver, flat-head, and slide over the dl under the heatsink. Make sure the screw-driver doesn't touch the board at all. You don't want to damage the tracings. Turn the driver slowly, pressing up on the sink and down on the dl. Use your left hand to pull the right sink corner up away from the board and to your left. Should come off pretty easy.
If not, try the freezer or hairdryer. Still stuck, go for the solvents. Hope this helps.
PS, if you can't understand my directions, please ask me to make it clearer.