Dell Studio XPS Desktop displays message, "Boot Device... no medium".

Hello,

 I was recently staring my Dell Studio Xps desktop when it told me to select boot device. I have selected every available option at least once to no avail. I am new to the online forum so this may be a beginners question but please help! I am running Windows Vista. I have heard perhaps my SATA cables may be incorrectly connected and I know how to reconnect these so if i have to I will. Please help!!! I received this computer as a hand me down and have not even got to the desktop screen once and I would like to soon. Thank you for all help!!!