Apparently there is no conflict despite your perception. Under NT-based
Windows, hardware is allowed to share an interrupt. What is *it* that
prevents you from installing the ATI video card? Does the system
actually work with the ATI video card installed? Or is it just you
trying to get it to use a non-shared interrupt? With the ACPI (Advanced
Configuration and Power Interface) HAL (Hardware Abstract Layer), you
don't get to assign resources until there is a problem with a device
(and sharing an interrupt is not a conflict). You will have to revert
to the standard HAL to let you change the resources used by a device
even when there is no conflict rather than having them automatically
assigned.
Which HAL employed in Windows depends on how your BIOS was configured
when you installed the OS. If the BIOS was configured to enable ACPI
then the ACPI HAL gets installed. If the BIOS was configured to use a
non-ACPI or standard setup then the standard HAL gets installed.
Changing your BIOS from ACPI to non-ACPI when ACPI was used when
installing the OS can result in instability of the OS and cause
problems; the OS may not even boot if it installed the ACPI HAL and then
you disable ACPI in the BIOS. See the following KB articles:
http://support.microsoft.com/default.aspx?scid=kb;en-us;237556
http://support.microsoft.com/default.aspx?scid=kb;en-us;306952
http://support.microsoft.com/default.aspx?scid=kb;en-us;246236
http://support.microsoft.com/default.aspx?scid=kb;en-us;246236