As long as you have a PCI-E slot using the 4350 should be fine. Depending on the board, both can be used at the same time(drive a screen off each for instance).
Since I had a 4350 in my media center(did not like the noise from the 5770). I do not think it will give you much gaming fun as it JUST pushes media center(the animations are not even that smooth).
I tried some games at the lowest settings, but that was about it.
In the end, I replaced it with a 650 ti and could not be happier. Cool , quiet and low power consumption(even games ok with some reduced details at 1920 x 1200).
my old card could run what i play better than the intel one
with the intel one its was barely playable
thanks for the info tho, i do plan to get a better card when i can afford it.