Win2k almost always tries to stuff all devices on to one or two IRQs (My laptop has 11 different devices on IRQ9, and my home system has 6 devices on IRQ9 and four on IRQ6). This is normal behaviour.
I would suspect your problem is NOT the IRQs. If you really think it is, the easiest thing (assuming you're a techie sort). Pull all the devices (except the video card) out of the machine and start adding one card at a time. Test after you add each card. If it crashes, pull out that card and set it aside and continue on. You'll probably find the problem device (though, as I said, I don't think this is your problem).