You have 4 USB controllers. The three usb-uhci are the USB 1.1 controllers, and ehci-hcd is the USB 2 controller. Now that I think about it, that one probably controls 2 of the same ports as the USB 1.1 controller does, though. But there are 4 controllers.
Disable the USB 2 in your BIOS if you don't need it, although I doubt that that'll help much, since the nvidia driver isn't sharing an IRQ with the ehci-hcd driver, but the usb-uhci one.
You can also just plain disable the onboard Ethernet in your BIOS, and put a PCI card in there. They cost about $12 for a new 8139 or FA311 card. Play with the slot that it's in until you get it on a different IRQ.
It might also help to disable ACPI. It's sitting on IRQ 9 all by itself; if you free up IRQ 9, then other stuff (like eth0, usb-uhci, etc.) might be able to move to that IRQ. Might be worth trying that before buying a new network card.
What order are these modules loading in? It might help to load the "nvidia" module first, and the rest of them after it. Maybe.