Can't install XP on Dell® Deminsion 2400

Hi there,

I have hit a very big hole here. I tried to install Windows 7, which didn't go so well. My computer is now as usefull as a dead moose. Now I've tried to install XP, which it originally came with. So here's my little 'story'.
"I turned on the computer. I pressed F12 on the keyboard when the Dell® screen came up. There was 6 options. I chose the third one, IDE CD-ROM Device. Then two seconds later, there was a message. 'strike F1 to retry boot, F2 for setup utility.'" Can you community please help?!