Sata Card for OpenSolaris, no raid needed
It's best if you check the OpenSolaris Hardware Compatibility Page before you purchase HW.
Supermicro makes an add-on PCI-X card that uses the same chipset as the X4540/Thumpers and people seem to have good success with it. Supermicro also has a PCI-e version, but I haven’t heard anything as far as compatibility.