I've been using my new customized HP Elite gaming PC and it's fast. I forgot how quiet a desktop PC can truly be since all my previous ones were mostly loud. They did a great job designing it. One thing I hate about it is that it uses a mATX motherboard and has all these stupid expansion hard drive slots on the outside of the case. Well, they're inside, but you can stick them in from the outside. To make it worse, you have to use their specified media drive, not just any ordinary external or internal drive.
The i7 line is definitely best for gaming so unless you plan to do anything else otherwise, I'm sure the i5 is adequate. I can immediately see the difference in gaming experience compared to my old PC. Fast load times, smoother graphics, more shading. Windows 7 is the best OS to date. Very nice features that make navigating a busy Desktop with ease. I love what Microsoft did to it.
On a final note, if you want to save money on a gaming PC, it's probably better that you buy a premade system through some manufacturer than doing it yourself. With the specs I have, I would've spent at least $600-$800 more!!!! That's money saved. Plus, I got a lot of nice hardware included like the memory card readers, upgraded high speed RAM, Windows 7 (never use the crack version because they're so unstable--always purchase), free keyboard and mouse, Norton IS 2010 for 15 months, TV tuner w/remote lol. Plus, the video card and motherboard supports HDMI so I can hook it up to HD!!!!! It has several eSATA ports too. The back and front are loaded with USB ports and audio/component ports. All that for just under $1,264!! After I configured everything from Newegg for a complete build, my lists went way over that price limit. That includes everything from a good PC case, power supply, down to the nitty gritty components inside the case .....but I do lose the satisfaction of picking out my own high performance parts though. I guess that's the sacrifice you give for a cheaper PC---but all in all, it's fast, plays games extremely well, and best of all, it has updated hardware and software for the future-proofing. At least for the next 4-5 years anyways