go for an Mediator , no matter what ...
grexx is dead, that openpci thingy...sure it might become a hit but its VERY unlikely to happen, also os4 for grexx ...forget it , wont happen unless DCE start to work as a team.
anyway as a last note, don't do the mistake i did...buy an MEDIATOR SX , thats the best choice, i know they cost more but u wont regret it.
when i bought the mediator, well that was before SX came , so basically i did'nt know

also..i had a grexx that died same day as i installed it , got too hot and melted some #### on it, still waiting for a replacement card...
this was 18 months ago ...so hurrah!..
NOT!!!!!!!!!!! ;(
cheers, and good luck effy