Windows 2000 doesn't give a fiddler's fart if your PnP option is on or off. The problem is the ACPI setting. If you use Windows with ACPI turned on, it stacks all your hardware to a same IRQ (IRQ11 in my case) and this could cause problems if your hardware don't like each other. I could only use my Motorola SM56 PCI modem if it was occupying an IRQ by itself. For this I had to turn the ACPI mode off. Microsoft actually recommends to turn the PnP off so I have it turned off and Win2k doesn't care. It functions as a PnP system no matter what. So go ahead and try turning the ACPI off. And if you still have stuff on the same IRQ try changing your hardware to different slots. You can find info how to change from ACPI to NON-ACPI here:
http://easyweb.easynet.co.uk/~stevemcd/win2000.htm
The only difference I noticed is that I need to actually press the power switch when I shutdown the comp. And ACPI turned off you can use APM if you want to use power management. Tell me how it went.