Ivy bridge vs 9800 gt

Hello,
I recently purchased new pc's for my 2 sons. I bought them kinda basic with the idea of upgrading later. They came running an Intel core I5-3450 Ivy bridge, Gigabyte GA-B75M-D3H, Onboard Video, DVI&HDMI, X-Fire, SATA3, USB 3.0, GB LAN, 1TB WD Green SATA3 6GB/s 64m cache, 4GB DDR3 1600 ram, Windows 7 Home Premium 64bit.
I intend on adding a new graphics card in the coming months. However, in the meantime, would we get better results by using the onboard video or installing their old video cards which was a Nvidia 9800 GT?
They play a wide range of games from Terraria to BF3. I realize even on low settings, the BF3 will be almost unplayable. Is the 9800 just too old?