You may see a small performance gain for the system if you fit a graphics card , At the moment graphics is using some of the system memory [ RAM] and that would be freed up.
I have just fitted the geforce 210 to a computer. Its working well . Good case fans would be important since it doesnt have its own fan .
The radeon is a more natural pairing for the AMD motherboard you have , but not worth the extra cost for your usage