You do not mention exactly which driver version you installed (latest is not good enough), and what the installation process was, that is important info.
Linux nForce Driver - IA32
Release Date: August 13, 2004
Release Highlights for 1.0-0283:
-Added support for 2.6 series kernels
That doesn't necessarily mean it will work with Fedora Core kernels that use 4Kb stack sizes. I haven't seen any info about using this driver with them, you may need to use the larger stack kernels. Search the forum for more info on that issue. Most nForce issues are posted in another forum: http://www.nvnews.net/vbulletin/forumdisplay.php?f=27
(search there for more, this forum is primarily about video)
Ethernet for nforce 1 is supported as part of the kernel, if that's all you wanted just use forcedeth.