Lenovo's IdeaPad series offers some decent choices ~$500 that can do what you want. I got mine for $420 with an Nvidia card that can run Civ V, Starcraft II, and even a bit of Skyrim at mid-level settings. MMOs vary, last I checked WoW was pretty light on your system at medium settings.
However, you'll be trading off support. Lenovo has some pretty dismal customer support and repair options if you happen to run into issues, and unlike "mainstream" computers where similar users have seen your problems, the IdeaPad market is pretty spread out so I often find it difficult to find solutions specific to my machine type.