So I downloaded and installed my kernel sources and ran:
./NVIDIA-Linux-x86-1.0-7676-pkg1.run --kernel-source-path=/usr/src/kernels/2.6.15-1.1831_FC4-i686
And rebooted, and it didn't work. /var/log/Xorg.0.log says that it "Failed to load the NVIDIA kernel module". modprobe didn't know what nvidia was. lsmod didn't know either. dmesg showed nothing about it. I did a lot of googling and came across this message which indicated someone with a similar problem had noticed there were multiple copies of nvidia related object files in his /usr/X11R6/lib/modules/drivers/ directory and that removing them and re-running the installer and editing my /etc/modprobe.conf to the following:
alias eth0 e100
alias snd-card-0 snd-ice1724
options snd-card-0 index=0
options snd-ice1724 index=0
remove snd-ice1724 { /usr/sbin/alsactl store 0 >/dev/null 2>&1 || : ; }; /sbin/modpro
be -r --ignore-remove snd-ice1724
alias char-major-81 cx8800
alias usb-controller ehci-hcd
alias usb-controller1 uhci-hcd
alias ieee1394-controller ohci1394
install ohci1394 /sbin/modprobe --ignore-install ohci1394; /sbin/modprobe raw1394
# all wonder remote
alias char-major-61 lirc_atiusb
alias lirc_dev lirc_atiusb
# nvidia kernel module
alias char-major-195 nvidia
#alias nvidia nvidia-1_0-7676
solved my problem. Your mileage will probably vary, but its something to try.
Oh, and I still haven't gotten firewire working with MythTV.