The GT 600 cards are nowhere near as powerful as the GTX 600 cards. They may be good for casual gaming, but don't expect to play Crysis on max settings.
EVGA's cards come in a few flavors. We have the GT 630, the GT 620, and a four variations of the GT 610. The 630 is a 128 bit card with 96 cuda cores and is clocked at 810 MHz. The GT 620 is about the same but the core is at 700 MHz. The GT 610 is a 64 bit card with only 48 cuda cores. It comes in a few sizes and memory configurations. The full height option gives you two DVI ports and one HDMI while the half height gives you one DVI and one HDMI. You can get either card with 1 or 2 GB of GDDR3.
They might be good for a media PC. However, if you are building a media PC you might want to look at an AMD APU or the Intel Ivy Bridge CPU's before you purchase a dedicated GPU.