UPDATE: Hey all-- I just got off the phone with Alienware and I've got some additional information now about these X51 desktops. I speculated in my original post that upgrades might be tough with them, since the amount of physical space inside a pint-sized PC casing like this is at a premium. It turns out that upgrades -- particularly for graphics cards -- are a snap. It's one screw and a release latch to get the outer casing off and the actual graphics card sits inside of an easily accessed tray. I hope that clears up any concerns!
ORIGINAL POST: True PC gamers will almost certainly chime in with comments about how it's always better (read: cheaper) to build your own PC by hand -- and they won't be wrong -- but Alienware tends to give pretty decent tech for your dollar. The just-announced Alienware X51 serves up a new kind of gaming PC, one that looks an awful lot like a gaming console.
Prices start at $699 for the Xbox 360-sized gaming desktop, though the top-level $1,149 unit is probably what you'll want to get for the best possible Battlefield 3 experience. The Alienware website even says so, with the product listing proudly touting that it is "capable of playing Battlefield 3 at 50+ frames per second with 1080p Full HD resolution."
Of course, the danger with highly specialized and compact designs like this is that you spend all sorts of money and then don't have the ability to swap out parts as they become outdated. If you're okay with spending a large chunk of money on a gaming PC that will play the latest games for the next few years -- at increasingly lower graphics settings -- then the X51 looks like a good choice. The compact size makes it perfect for those who want a PC connected to their TV.
The two lowest price models, available for $699 and $899, respectively, both come with an NVIDIA GeForce GT 545 GPU installed. The cheaper option has half the RAM, at 4GB vs. 8GB. The big difference, however, is the CPU: for $699 you get an i3-2120 3.3 GHz and for $899 you get an i5-2320 3.0 GHz.
The two high-end models ($949 and $1,149) also share the same GPU, an NVIDIA GeForce GTX 555. The RAM difference is 6GB vs. 8GB. The cheaper model uses the same CPU as the $899 option, while the more expensive one packs in an i&-2600 3.4GHz processor. Be aware that hardware customization is limited with the X51; pretty much everything except for the optical drive is standard.