I have an older gen 5 dell XPS and was having issues with the windows 7 DVD booting, I tried everything from updating the firmware of the drives to updating the BIOS, moving and making the only thing bootable device my CD/DVD ROM drive nothing would work. I didn't want to take the time of burning extra disks or buying a flash drive to try that boot option. I finally was able to get it to boot by going into my drives and turning off my pata 0 drive wich was my CD ROM (master) leaving only my pata 1 drive on which was my DVD (slave) this made the DVD the master drive without switching cables and allowed windows 7 to boot no problem, from there installation was a breeze. I'm not a super tech when it comes to OS installation but i didn't find this resolution suggested and thought i would throw this up incase anyone else with an older Dell is having similar issues. I hope this helps and saves someone the time it took me to figure this out stumbling blindly through blue bios screens Good luck !