not really - only you want to do it the Debian-way.
You can also download
a) from any Debian-repository the fitting kernel-headers 2.6.26 (i.e from the
stable (aka known as LENNY) branch).
b) or Download the complete kernel-source from kernel-org and compile a
completley NEW kernel. This way is much more intensive, and I think you
wont't do so, because you have an exisiting / running kernel with which you
After doing a) you can run the NVIDIA-installation program (Download it from
the NVIDIA Homepage (the ONE that I use is: