I usually go with Alienware. They are a bit pricey, yea, but I don't like to hassle with building computers and I like to have a more mobile computer
Saving up for a m14x atm, the specs look a bit similar to yours if you upgrade the gpu, and its somewhere around 400 bucks less? I might need correcting on that tho if it's got some hidden advantage I'm not seeing
EDIT: RAM is a bit lower on the alienware, but its like 8 GB.