There are no split connections for SATA cables as Punky stated. SATA is a serial connection which only allows one connection at a time. You have two options. First you can change the drive with a PATA (often called IDE) drive or you can purchase a SATA controller card to add extra ports to your system. The following card is cheap in price and should work well in your system:
http://www.newegg.com/Product/Product.aspx?Item=N82E16816124012I hope this helps. Good luck.