Widows Seven

Hello,
When trying to install the windows seven release canidate my computer coe up with " disk boot failiure , insert system disk and press enter." so i put another win7 disk in to see if it'll read that burn , get the same error. i've gone to the boot manager to selected the disk to boot from. When i try to install Vista i get"Error, Can not read D\: sources\****.win please resart and insert disk."