Changing IRQ

I am installing an 802.11b network, using an Orinoco RG1000 gateway with PCI Adapters with G.old PC cards. A Agere support person said their cards did not work right using IRQs above 15. In two Emachines with XP the computer assigns the IRQ or either 16 or 17 even though 7 or 10 are available. Device mgr says these IRQs cannot be changed. How can I change them, and was the tech man correct when he said 16 or 17 would not work? Ths signal radio signal is good but no network name is seen.