To compile the nforce drivers on debian I had to
This is when using the stock kernel from the kernel-image-2.4-k7 package. The Makefile makes some assumptions about where the headers are supposed to be (using uname and some redhat specific assumptions i think) so you have to specifiy. If you've built the kernel from source export SYSINCLUDE to the include directory of that tree that you've compiled from and you should be ok.
You only have to do this if you're getting the missing modversions.h error
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