I mainly designed this build with gaming in mind. I'm not a heavy multi-tasker, so the Pentium works fine for me. If you need a faster CPU, bump it up to an i3 4160. I chose the GTX 750 Ti mainly because it was on a pretty good sale, and it runs much cooler than the 260X, as well as being less power hungry. You can take out the optical drive, it's completely optional. I just included it because it makes installing Windows and drivers much easier. You can swap out the RAM to save a few bucks, I just chose the G.Skill because it was on sale, and I kept it in here because I can confirm it works. All of these parts fit inside the case quite comfortably, but the cable management space behind the back panel is limited, so you won't be able to route thick wires through there. Everything works perfectly, and this was my first build, so that's proof that it was pretty simple to assemble. Just a word of advice for other first time builders out there: Make sure you push down on the ram REALLY hard. For a while the system wouldn't POST because the RAM wasn't seated well. Sometimes it would beep to indicate that no RAM was detected, but sometimes it wouldn't, and it still wouldn't POST. The key is to make sure you hear a snap. After I did that it worked perfectly. (BTW the included temps might not be what you get since my rig is up against my fridge so... yeah)
UPDATE: I've overclocked my Pentium to 4.3 GHz @ 1.3 Volts and my 750 Ti to 125 MHz over stock core clock, and my GPU memory to 30 MHz over stock. I don't know if it makes much of a difference performance wise, but I wanted to get the most I could out of my parts.