Putting together a PC is easy enough. I did it on my own with no help from anyone. Just did a little research and slapped it together. I mean, 50% of building a computer is fairly common sense (Gee, this must go in this slot because its the only slot that fits... =P)
The Core i5 build is superior to the first computer listed, but as inzone said you'll have to build it and that's a different ball game than just buying it. An easy ball game IMO, but a possible frustrating one if you are new at it and not prepared for any issues that can arise. Not to mention the build is higher priced.