I have to guess - is this a laptop or desktop? Idk the AMD chip, but for the Nvidia:
desktop, the Nvidia has driver support
laptop, Nvidia has a reputation of running hot enough to burn the motherboard. See Researching Linux laptops - openSUSE Forums
for more detail, especially oldcpu’s posts in that thread.
The AMD and nVidia are both good. There may be other parts that are not compatible though. Could you get a run down on all the parts he is planing to use? Network cards, especially wireless can cause wailing and gnashing of teeth. WinModems as well are quite problematic.
Typically when checking for compatibility with a graphic card, one gets a bit more detail as to the exact card model # (ie GeForce FX5200, or GeForce 8400GS, … etc … ).
GeForce 8400 GS is cheap, widely used and well supported by both open source (nv) and proprietary (nvidia) drivers.
GeForce 8200 found on several mainboards (ASUS M3N78 family) is NOT supported by the nv driver and might have problem to install under openSUSE.