Sure, if you can afford it, AlienWare is an excellent gaming puter sysetm with multiple processors, out-of-sight graphics, video, and sound, but then if you had that kind of money, you could probably buy a puter for each function!!
I have been gaming from a Commie 64 up through the ranks of IBM and forward, and have used almost every make of puter at some point. The curtial aspects are
1. if you can do-it-yourself,
2. if you want to buy a system and just use it.
If you can add to a puter, I have found that e-Machine is an excellent upgrader, and if you get somewhere in the top of the line, you will have plenty of slots, ram space and areas for hds, the e-Machine I ended up with when I was done was running at 2.5 Ghz, had a 512 Rad. video card, top of the line SoundBlaster, 1 Gig Ram, 200 Gig HD, and other little goodies, all picked up on sale for a song after rebates. That was my ''extreme gaming machine'' though I lost it through an unfortunate life experience.
As far as out-of-the-box systems, I have used Dell, and the newer (since the combination of HP and Compaq) Compacq, with I am currently using for gaming as I purchased a fairly decent one on sale. 2.5 Ghz, 512 Ram, 128 video, 200 Gig HD, and a very decent sound card in a AMD 64 3400+ Compaq Presario bundle. Straight out of the box, I could play any game I have, such as Halo, Unreal Tourney 2004, BattleField 1942, and other farily intensive games with just a few tweaks of the options in each game.
SO, as I am more than pleased with this particular system, I would have to recommend it for both gaming, general puting, and even a home wireless network system with 2 other puters here.
Hope this helps a bit.