It seems you know what you want.
While I've never given it much thought, any gaming and I'm off to tomshardware.com to see what the best video card for the money is. Also, I think the new standard is 8GB RAM. And a nod to the i7 CPU.
Good hunting and hopefully who ever designs this machine has learned all the install lessons and will DOCUMENT HOW TO INSTALL WINDOWS if that's the OS you intend to run.