AWhackWhiteBoy is right on that one. ABS Computers are very top notch computers, and lets not forget about the relationship to Newegg .
My sister bought a PC I configured for her on ABS a long time ago. It was a 1.2Ghz Athlon (thunderbird core, obviously) and you know what? She's selling it soon to someone cheap and her new Athlon 64 3200+ laptop is coming soon. This PC never had ANY problems. Nothing ever went wrong with it and she never had to replace anything, and she used it a lot every day.
I would strongly suggest ABS Computers' Gamer-oriented PCs over Alienware's. For one thing, you get the same thing for cheaper and you can choose the wavemaster case I like that case over the alienware case. Alienware PCs don't suck, but my cousin also got an ABS PC (I could have built them...but like one person said, if you have the money why bother with the hassle?) a while ago. When a friend bought an Athlon 64 gaming rig off of there, it came already optimized as well, but $500 cheaper than Alienware. Either way, you can't go wrong if you have the money to spend on it.
I have built many PCs and I would go with buying it pre-built from either one of those two because I have no time to sit and build a new PC, install OS and programs, optimize if needed, etc. DIY PC, Alienware or ABS-built...you can't go wrong .