\"Under Windows XP Microsoft has significantly improved both interrupt handling and ACPI. In most cases the interrupts will not be sharing IRQ 9. Even when, problems like with the above mentioned simultaneous network transmission are no longer found. Furthermore XP operates more reliable and stable using the ACPI mode. Therefore changing to Standard-PC mode under Windows XP is not recommended.
The worst thing to do is to use Standard-PC mode with the latest generation of single CPU motherboards, having an advanced programmable interrupt controller (APIC.) These boards offer 24 interrupts under Windows XP in ACPI mode (else found on dual CPU boards only) - but only 15 when using Standard-PC mode!\"