The 210 has basically identical performance across the board as the 9400. I would choose the 210 over the 9400 however, since the performance like i said is roughly equal, and because the 210 is based off a newer 40nm process which means it uses less power and runs cooler. However if you decided to increase your budget, i'd suggest the GT 220 or the ATI Radeon HD 5450.
But as long as your not using a very high resolution the GT 210 should be alright.