No graphics card for the Dell? ;)
Assuming the graphics card is similar to the one in the Cyberpower, the Dell would be a better choice. 6GB of RAM is plenty. The CPU is more important.

Between Dell and CyberPower, CyberPower Has a Graphics Card And Dell Does Not.

-Lean

First of all, you should never buy pre-built. Always build a custom pc, always always always. But if you don't want to, here is what i'm going to offer.

So going from that let's talk which computer you want:
The Dell, with a catch. For your low end gaming with a low end budget this is really your best bet. The CyberPower is good, but the processor really ruins the whole thing. 8GB of RAM is way overkill for "low end" stuff. The 6 RAM in the Dell will be more than enough to support quick multitasking and quick gaming. The Dell processor is better than that of the CyberPower, the stats clearly show that. But here's the catch with the Dell; you are going to need to upgrade the graphics card for gaming. I know this kind of sucks, but investing $100 in a GPU will be worth it. I bought my GPU over a year ago and I still play games fine (cod4, tf2, bfbc2, l4d2). It only cost me $100 and I don't regret it. So, if I were you, I would buy the Dell and spend another $100 on a GPU. If your budget is THAT low, buy the CyberPower.

Buuuuuuuuuuuut; none of this is relevant because you should BUILD FROM SCRATCH! Seriously, you can build the same PC for $75-100 cheaper. I hope I helped you out. Buying a PC is all about what you want, so do your research. When buying a computer if you're not spending 5+ hours researching, you're not ready to buy.

Ok, I Did order the dell. Which Graphics card should I be looking into? I thought about just buying the card that was on the CyberPower. The AMD Radeon HD 6450.