I feel this thread has reached critical mass in terms of poor advice, so how about we share a nice glass of "educated opinion"?
Getting a customized, pre-built machine from Dell or any other OEM doesn't make you the class dunce, and certainly isn't a bad decision
in all cases. For a gaming computer it may be worth the time to build one yourself from parts; you often times save money, you have more control over what parts go into your machine, and you can learn valuable information about how a computer works and how to fix it if something goes wrong. The only significant trade-offs are that you must build it yourself (which can be a challenge) and you must handle any technical issues that should arise.
So, assuming you decide to build your own computer, what parts should I pick?Let us start by selecting the
processor we wish to use. There are various benchmarks, both artificial and real-world, that compare different CPUs to each other. You can see an example of such benchmarks
here. What processor you end up choosing for a gaming rig mainly depends on your budget; whilst a Core i7 processors are quite powerful, they require the use of a more expensive chipset which will drive up the price of one of the other components you will need to purchase, the motherboard. On the subject on Intel vs. AMD, I'd caution you to not heed HPRC's advice as the number of GHz or cores that a processor has are not good indicators of performance
across brands. A 3.0 GHz quad-core AMD processor may not be more powerful than a 2.8 Ghz Intel equivalent.
My recommendation would be to go for the Intel Core i5 750 processor; it is quite powerful, it is affordable, and it will easily meet your needs for the considerable future.
I'm afraid I don't have time right now to finish this post, but I will update it this evening with the remainder of my recommendations.