on the IRQ thing.. if have Win2k or 2pro, and you are sharing lots of IRQs its probably because your computer is running in ACPI mode.. in device manager click computer, of its says ACPI or anything else, double click that and go to update driver and changed it to 'standard pc' that after reboot you will need to reinstal some drivers, but everything will have its own IRQ automatically.
ACPI tries to save as many IRQ numbers as possable.. and lumps many devices on to one..
after changing it I went from 29fps to 37fps.. sitting on runway in P51 in 1600x1200x32.