IANAL, but reading the license it looks like you can't mix
different versions of the kernel and userspace components
of the nvidia binaries.
"
2.1.3 Limitations.
...
No Separation of Components. The SOFTWARE is licensed
as a single product. Its component parts may not be
separated for use on more than one computer, nor
otherwise used separately from the other parts.
"
BTW, what functionality of the nvidia binaries don't have
counterparts in available open-source drivers?
/Jonas Sundstr闣. www.kirilla.com