Do you want to use anything for which you need good graphics drivers?
In that case, take the one with the Nvidia card.
Just look at the three dozens of threads about "installing ATI drivers". It's particularly bad right now since Fedora 17 is very new, but apparently it's the same story every time there are updates to Fedora.
The xserver-driver included with Fedora do work for Radeon cards, but they don't work well. Things will look ugly compared to actual Catalyst-drivers. If you can get the catalyst drivers to work.
With an nvidia card, all these problems don't seem to exist. It's not the hardware or even the software, but more how the two companies approach creating new drivers and making sure they work with linux. Nvidia is careful and pays attention, the people who make the Radeon drivers don't.
Oh wait! A Radeon HD 4500? For that one there won't even be any official drivers that work with Fedora 17 and any future versions anymore. With that computer, you'd have take the standard xserver drivers without having a choice.