Yes, your machine has a pcie *16 slot available.http://i.walmart.com/i/rb/0088448353767.pdf
Just make sure any card you want to get can fit in that small computer.
Be advised, it looks like the slot is a pcie *16-1 and not a 2.0. Newer pcie 2.0 cards will not work at full power.
Also, keep in mind the PSU gives only 220W, and I don't think that will power anything worth buying.