I'll just be straight up and tell you if you are willing to build your own it is so much more cost effective and you get a much more powerful system for the price.
Building your own means you usually get a warranty for each individual peice of hardware (Ram,GFX card, Motherboard, Psu, Cpu) as opposed to getting one extremely limited warranty for the entire system. It's much easier to RMA a single part rather than be computerless because you had to RMA the entire system.
Building your own also means you get better quality hardware and just more powerful hardware in general for the money spent. The prebuilt computersm, even the so called (gaming computers), will ususally have low quality PSU's and motherboards to skimp on cost to make...