OK well it looks like you have Onboard graphics. Best i would recommend without an extra power source is the 4650 or 4670
They about the most graphical power you can get without an extra 12volt power source. But still it be nice to know how many watts you power supply puts out.
Nvidia 240 or ATI 5570 might be another option if your looking cheap but want the newer gen tech.
Granted these wont play nothing like crysis but if you got by with onboard graphics this long, Im pretty sure this will get you going till you need another PC
Since you look like your running a stock machine i would recommend a new power supply if you want a graphics card with some real power behind it.
What are you PC specs anyways?
Far as brand name? doesnt matter to me ATI has been known to have more drivers issues with Crossfire configurations but i never had a problem.