Are you using the default nv driver, or the nvidia driver? I'd check that before you went ahead and downloaded xf86.
As for 4.3 locations, i found a source from apt-get.org. just add the following into your /etc/apt/sources.list file:
deb
http://debian.netfarm.it/experimental/ woody sherpya
I'll warn you though: I'm on a dsl connection, and that downloaded at about 5k/second, taking almost 5 hours. I'd definetly recommend looking around apt-get.org again to see if you can find another source.