I have a IBM Netfinity 5500 M20 with 3 CPU's. Since installing Windows 2000 the server gets about 60000 interrupts/second (20000/CPU). I've read that this can be related to ACPI. But when I check the BIOS for the motherboard it says that it's fixed ACPI support for Windows 2000 in version 1.05. My server has version 1.06.
I found the answer elsewhere. I had to disable my printer port. Very strange. But then all interrupts went away.