This has been discussed many times.
But since you didn't supply a make or model no one can give the details about such a downgrade. You MUST have a full Windows XP SP3 or XP SP2 CD. Trying to recycle some old XP CD from another machine or say "XP" or "XP SP1" is known to be trouble.
Sorry that we can't start the conversation but it looks like you could try again with details if you want to see if this machine has Windows XP drivers.
THE NEW COMPUTER I PURCHASED CAME WITH WINDOWS 7 INSTALLED. AFTER DEALING WITH EYE STRAIN AND HEADACHES FROM THE FUZZY FONTS AND BRIGHT BACKGROUND FOR A COUPLE OF MONTHS, I WOULD LIKE TO GO BACK TO WINDOWS XP. MY QUESTION IS......IF I CAN OBTAIN A NEW COPY OF WINDOWS XP, CAN I INSERT IT INTO THE CD/DVD DRIVE AND WILL IT INSTALL ITSELF OVER WINDOWS 7 OR IS IT MORE INVOLVED?
THE PROBLEM IS NOT THE MONITOR AS I HAVE MOVED IT TO AN XP MACHINE AND HAVE NO FONT PROBLEMS. I HAVE ALSO PUT ANOTHER MONITOR ON THIS WINDOWS 7 PC, AND THE SAME PROBLEM WITH FUZZY FONTS APPEARS.
IF I CONNOT GET THIS PROBLEM RESOLVED, THIS NEW PC WILL BE AN EXPENSIVE BOAT ANCHOR.