It enables the effects (compiz-fusion pretty surely) if it seems the hardware can do it. For ATI cards that means you need to have the ATI graphics card drivers installed that provide hardware accelaration; see ATI website for information on your card and if it's supported by the Linux drivers they provide.
If their site provides Linux drivers for your architecture (32- or 64-bit) for your specific card model you can either download the driver installer there and follow the instructions given by ATI, or see if your package manager happens to have a Fedora-team-made package that has the drivers. The package manager solution is easier, but if there is no ATI driver for your card there, then the installer from ATI's site is your only option for that driver (and if it doesn't exist, then it doesn't). After successfully installing the drivers, restarting and still having your X working you can re-try enabling the effects. Note that the case is often worse with built-in graphics cards than those that are not.
One option, if there are no drivers for Linux for your card model, is to try out the Mesa drivers. Not sure how well they work, how easy they are to install nowadays and if it works for you, but it's a chance at least..