What's wrong with Vista? I am running Vista Premium Home and have not really had any issues with it except for UAC for which I have found a way out of. Mines is the 64 bit version and really no problems there either.

I think you are going about installing XP the wrong way. The first thing you need to do is to to Dell and download all the drivers for XP. Go to Drivers & Downloads

After you have downloaded everything you need you stick in your XP disk and boot up, format the hard drive, install XP and then use the files you downloaded to get your video, sound, modem, lan, etc working.