This post is specific to enabling 3d (desktop effects) in fedora 13 running on Nvidia graphics. I struggled to enable the desktop effect in Fedora 13. But eventually I managed to enable the desktop effects using the following steps.

Note: This is a 3 steps process. Please follow all the steps to enable desktop effects in Fedora 13

1. Install Nvidia drivers ( if you have 4Gb of RAM or more you will probably have a PAE kernel [32bit only] so follow the PAE part )

su
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
yum install kmod-nvidia xorg-x11-drv-nvidia-libs.i686

If you use a PAE kernel

su
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
yum  install kmod-nvidia-PAE

2. Edit the Grub File

su -
sed -i '/root=/s|$| rdblacklist=nouveau|' /boot/grub/grub.conf
mv /boot/initramfs-$(uname -r).img /boot/initramfs-$(uname  -r)-nouveau.img
dracut /boot/initramfs-$(uname -r).img $(uname -r)

3. Reboot

Once you have rebooted go to System > Preferences > Desktop Effects