Yeah, as long as your motherboard has a PCIEx16 it can use pretty much any current card. The better questions are whether it will fit in the case(likely, it's not that big) and whether your power supply can handle it.
As for what card you should get in general it depends on your general system specs, your monitor's native resolution and your budget.
I already upgraded my power supply to a 500w unit, so i think im good there. I know that i also have to worry about the case, but why i ask is that if you look at the diagram, the pciex16 slot is almost in front of the ram slots, so i was asking if the card were to touch one of the banks/actual memory modules, would my system still work?
Oh, and is socket am2+ an actual different and socket than am2, or does am2+ just mean socket am2 and higher (am3)?
I will think that i should just get the 5750 XFX card. Ive been reading its reviews and they say that it runs crysis preety well (mediaum - high at 30+ fps). Crysis is such a highend game that even at medium to low settings look like reality!