If you don't feel comfortable with building your own because of your lack (perceived) of assembly and troubleshoot skill, it's a legitimate option to buy a pre-built system. It seems that some people here have firm belief that buying such completed PC is almost a sin, unfortunately. If I didn't have experience troubleshooting/repairing previous Dell and Gateway PC, I would have been hesitant to build my own. I saw many people struggling after they built their system, even for the second or third time. If you are not a type of enjoying such challenge, it may not be worth your efforts and anxiety. You can start building PC later once you have basic knowledge in PC handling through many troubleshooting and minor repairing when the needs arise as your system gets older.
Having said that, the iBuypower PC looks good, but I would go to their own website rather than buying through BB. I am not sure if iBP will provide the same customer service even if you buy from BB, but assuming the worst, BB customer service or Geeksquad is not your best bet when you face problem later. The reason you buy from such boutique builder is to have comprehensive customer service, and I think you better buying from them directly to minimize possible headache later.