I don't think this PC will cut it for games. As far as I can see the 5450 is not really capable of churning out decent framerates even at medium settings. This being a brand PC I can pretty much guarantee that they used minimal components for the power supply and motherboard, making simple upgrades such as slapping on a good graphics card a non-option. I got my PC from E-bay (great price, had to put in my own harddrive though). If you find a custom gaming PC on auction, it will most likely be a machine that can be upgraded (a powerful power supply, good SLI capable motherboard will allow for easy performance tweaks).
Just my two cents.