I don't know the exact specs that are good nowadays since I don't PC game. Look at the recommended specs for a current game say Bioshock Infinite. Since you're not building you own computer, get a machine with at least the recommended game's RAM and CPU (for Infinite, that's 4 GBs of RAM and a quad-core processor). I would prioritize getting the best CPU for your price point (RAM is real easy to install more of) to future proof your machine as much as possible because you can't just switch out CPUs like you can video cards, getting a better CPU usually requires a new motherboard. Then, go and buy the best $100 video card you can find, they are solid cards and can run the newest games. Just using that method, you should have a pretty good machine that will play games for a few years. You then have the option to upgrade your video card in couple years and spend another $100 and get a card that's like $400+ now. I'm pretty sure most pre-built computers with a good video card are way overpriced like say an Alienware. Don't by a laptop for gaming, you can't really upgrade them much.