Can't reinstall Win XP to Dell 8300

After getting the blue screen of death I tired to reinstall XP, but I can't get to the XP CD when I start the PC up. I've set the boot sequence to CD ROM first then HD, but still it goes immediately to the Win start up screen then goes to blue and just keeps cycling unless I hit F12 and then it asks me the usual start up ?s e.g. normal, safe mode, etc., I've tried every option and still it either freezes as it's going through the files (at file AGP440.xxx), then I manually shut it off. It just doesn't want to recognize the XP CD. I have both the DVD and CD drives should I disconnect one? I also have an external HD do I need to remove that too? Help I've crashed and I can't get up!