We picked up this card because Promise claimed it was Linux Compatible. Bung. Binary-only drivers for micro-specific distributions makes this card moslty useless in any production Linux environment, which I could never in good conscience recommend any of our clients use it. Giving up on it and selling the card to someone else. Currently in the market for some 3Ware goods.
See
this page for a more thorough investigation.
In short - if you want to run an old outdated kernel that you can't update then this thing might work for you. Try a Google search for "sx4000, lkml" and get a better insight into why not to use this card in Linux.