My suggestion would be to find a windows 7 machine this is up to date on patches (That is how most drivers are delivered) and see if it works. XP and USB aren't really the best combo for newer devices imho. Sounds like you found the problem though (Multiple NICs not playing nice)....
Another suggestion might be to use the wifi hotspot option instead of USB. I've been using FoxFi (No tether plan) and its been working wonderfully with my N7 tablet.