If your BIOS supports setting PCI/ISA cards to specific IRQ's this will work, if not it's entirely possible through the embedded BIOS strings that the Network Interface Card (NIC) will be forced to a 16-bit IRQ which is something above IRQ 9.
The only way to find out would be to disable the Com port and any other device that you are not using in the BIOS and then reseat the NIC in its slot. Microsoft should still see the card with the driver that's loaded. The IRQ change should only change what the NIC is on and not what driver or o/s setting it has with other operating systems.
I'd consult the manual for the motherboard before proceeding though which you can search for with
http://www.Google.com unless you have the manual in hand.