You have an upgrade copy of xp. You need to do exactly what it says. Put in your older windows disk that you are upgrading from and it should work. Pretty self explanatory.
Are you holding the F6 key down at any point during installation?
What motherboard?
"Setup cannot find a previous version of windows installed on your computer. To continue, Setup needs to verify that you qualify to use this upgrade product.
Please insert your Windows 3.51, Workstation, Windows NT 4.0 Workstation, Windows 2000 Professional, Windows 95, Windows 98, or Windows Millennium CD into your CD-ROM drive."
You have an upgrade copy of xp. You need to do exactly what it says. Put in your older windows disk that you are upgrading from and it should work. Pretty self explanatory.