You said "if I instead boot to Windows or another Kernel that doesn't load X".
What do you mean exactly? Do you have to start Windows until Windows enables a hires graphics mode, or is it sufficient to just have it boot a little and then kill it (yes that's evil)?
What is the behaviour if
- you cold-start your current kernel, but not X, then warm-reboot and start X this time (with the new driver)
- you cold-start your current kernel, X using the nv driver, then warm-reboot and start X
- you cold-start an older kernel, but use the current drivers?
Have you tried commenting out all those extra options in XF86conf, like BusID, VideoRam, etc.? Just to be sure...