Well,
Mubbers, you can either keep aside the 160SATA for future use, or, buy a PCI SATA card and use it there. That option will bring you down to PATA data transfer speeds as the PCI bus does not support current SATA data transfer speeds. (150mB/s SATA vs 33/66mB/s PCI Bus speed)
On a different note, you mentioned that your intent for this setup was for gaming. Just to let you know, RAID0'ing the two Raptors will not net you any increased gaming performance, as gaming is CPU/GPU intensive and does not rely on the HD's for faster/smoother gaming speeds. About the only thing this setup will help with gaming is that it will load the actual game faster than before. Once you start playing, you will not notice any significant game speed increases.
Heeter