I succeeded in getting graphics to work on my Gateway DX4720-03 by installing the proprietary nVidia driver, following the instructions at http://rpmfusion.org/Configuration [1] and then http://rpmfusion.org/Howto/nVidia [2] (specifically: yum install kmod-nvidia)
RPM Fusion does not have the very latest nVidia driver (available at http://www.nvidia.com/object/unix.html [3]), but the one they have works for the nVidia GeForce 7100.
For the record, the Gateway DX4720-03 also needs the kernel option "noapic" in order to boot.
The next time I buy a PC I'll steer away from nVidia hardware because there does not seem to be any open-source driver for it. Hardware that requires a proprietary driver is invidious.
Links: ------ [1] http://rpmfusion.org/Configuration [2] http://rpmfusion.org/Howto/nVidia [3] http://www.nvidia.com/object/unix.html