If you’re wanting to use the nvidia proprietary driver, rather than the nouveau driver provided by default in Fedora 15, then do the following:
1. Add this to the end of the kernel line (without quotes) in /etc/grub.con f -> “rdblacklist=nouveau vga=0×318″
2. Command : su -c “rpm -Uvh http://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-stable.noarch.rpm http://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-stable.noarch.rpm”
3. Command : yum update
4. For 64bit Users, Command: yum install kmod-nvidia xorg-x11-drv-nvidia-libs.i686 xorg-x11-drv-nvidia-libs.x86_64
5. A) For 32bit Users, Command : yum install kmod-nvidia xorg-x11-drv-nvidia-libs.i686
5. B) For 32bit Users using the PAE kernel, Command : yum install kmod-nvidia-PAE.i686 xorg-x11-drv-nvidia-libs.i686
6. Reboot, and you’re done !
Note: If this doesn’t seem to work for you, in step one , instead of “rdblacklist=nouveau”, try “nouveau.modeset=0″