Need help picking a graphics card

[s14kouki]

My dad recently bought a new PC its a HP p6127c 2.3GHz Q8200 6gb all that is good except for the Intel GMA 3100 card. I have a friend that says my PC would be all set to play the newest games if only i had a better card, i really want to be able to play new games like Empire and Napoleon, i can run Medieval 2 Total War but once i get to many units the FPS drops and gets really choppy. I really dont know much about computers besides basic knowledge and there are so many different graphics cards out there so i was wondering were i should start. Also my friend said since i have and integrated card i have to have a PCI slot which i think i have and he also said i might have to get another fan!!! There are so many different graphics cards i really dont know were to start so any help will be appreciated.

[irishron]

You have a pcie x 16 slot but only a 300w power supply. I don't know how much room you have for airflow to keep it cool so be careful.