hi,
the crystal orb will physicaly fit, but the pin things wont align up right so you`d have to use some thermal epoxy.
thermaltake tend to release a new GPU cooler for each new series of the geforce cards. blue/orange orb for gf1/2, crystal orb for gf3 and the gf4 copper cooler.
i`d buy the the gf4 copper cooler personally cos it comes with some ram sinks. but, if you already own a crystal orb, then buy some thermal epoxy, but, for the same price as the epoxy, you can get the gf4 copper cooler, your choice really.