The answer is no, you cant RAID a SATA and a PATA
You will have to remove the IDE ribbon from the PATA, plug the SATA in and Install XP.
When installed and you have updated XP, then you can plug the PATA drive back in.
Now ensure you boot to the new installation and then copy all your documents over to the new SATA drive. Then format the PATA drive and use that as the slave for all your documents