please tell me the order in which all the PCI slots are taken..
it may just be that your motherboard cannot assign a seperate IRQ to that slot. if so, then you should try enabling ACPI.
go to the control panel/system icon.. then go to device manager, and go to the system devices group.
double click on the PCI bus icon, go to the irq steering tab, and check the 'get irq table using ACPI BIOS' check box.
make sure in your BIOS in the PnP devices area (or something similar) that 'PnP OS Installed' is enabled, or true..
that SHOULD allow the devices to share IRQ's without any problem, it fixed my problem with my Hollywood + sharing with my PCI modem (cause they were on slots that shared IRQ's).