How do I remove XP Setup Screen

I recently tried to upgrade a Windows 98 machine to Windows XP Professional. However, I failed because the machine’s BIOS is not ACPI compliant. As a result, I had to revert to the existing 98 operating system. The problem is, when you start up the computer, it shows the option of starting with either the Win98 O/S or the XP setup. If you are not there at startup, it automatically goes into the XP setup and then hangs at the point where it tells you that the BIOS is no ACPI compliant. How can Iremove the XP setup option, or if possible, bypass the ACPI compliancy screen and complete the XP upgrade.