IBUYPOWER vs Alienware vs CyberPower?

I've been debating between buying a custom PC from one of these 3 suppliers. The only thing that upset me away from Alienware is the price (insanely) ridicolous. Both ibuypower cyberpower and allows me to customize a PC for $ 2000, equivalent to a PC that costs $ 3500 Alienware. I know this person bought a PC custom built for $ 3000 (do not know where) and it works, but works like crap. When I asked why, he just said "the pieces do not fit, "which makes no sense to me because, if the parts were not compatible with the PC would not play. So I'm just wondering if I'm running the risk of not having my pieces fit 'If I buy from Cyberpower opposed to Alienware. I was inclined to this PC http://www.cyberpowerpc.com/system/Gamer_Xtreme_XT/ with: GTX 295 i7 960 6GB DDR3 RAM standard 1800GHZ motherboard – MSI X58 Pro-E Intel X58 Chipset

Alienware is owned by Dell, will cost an arm and a leg his best bet is to build your own and buy a Windows disk with it. go to www.tigerdirect.com or www.newegg.com have barebone kits as well as you can build Sheet alienware that is what I did: P