HIS IceQ 7750 or Geforce 550 Ti (Imediate response needed)

Hi, im looking to decide which card to get... I would like it if you could even possibly recomend me one to. But right now im just looking at the 550 Ti or 7750.

So my system:

CPU: Athlon II X4 635 2.9GHz

Motherboard: Foxconn model 2AB1

Current GPU(s): HD 4200 integrated and MSi Geforce 210 1gb

PSU: Diablotek EL series 500w

And along with all of that i have a crappy seagate barracuda 7200.10 160gb and 12GB of ram

So.. with all of that down this is my first post so sorry if it isnt good format or anything i am in the 125$ range plus i could handle about 10$ more for shipping if i need to or tax whatever.. So yeah if you could recomend something better than the two cards i mentioned then feel free.

P.S. Shipping i only use Newegg and in store i go to microcenter at st.louis, Missouri.