Video Card for Dell Dimesion 3100/E310

Hello,

can some one please suggest a video card for my dimension 3100 / e310 desktop ? I bought a new dell monitor SP3209W and I still have a old integrated intel video card in my desktop. I would like to upgrade it something decent that can support good resolution for my monitor and also a little bit of gaming. I am not into very graphic demanding games . Also , I dont know if my desktop has PCI express slot  but I know that it has two PCI slots. I dont know how to confirm if my desktop has PCI express slot so if someone can guide me that will be great.

Thanks for your help