Black PCB is always nice. What about silver PCB's like Triplex used to do with their GeForce3 and GeForce4 cards? They were pretty unique I guess, in that respect at least. They were pretty rare, I believe they were never released in North America, just Asia.
Triplex Millenium Silver GeForce4 Ti 4600
Triplex GESTAPO GeForce3 Ti 200
(
Note: GESTAPO? Interesting name.)
But like I said, black is always nice. I guess if your really got to use green, how about some darker green?
By the way, the card you are giving away, the 8800GT 1GB, it's a pretty un-attractive card. Green PCB, blue HS, and red DVI ports? Ouch!