With its lightning-quick CPU, newest Android version, great touch screen, and NFC chip, the LG Optimus 4X HD is firing on all cylinders.
AMD's new Phenom X4 9850 is overpriced and outclassed compared with its Intel-based quad-core competition. If PC vendors can use this chip to make cheap systems (as they did with older Phenoms), we might have nicer things to say, but as a DIY part at this price, we can't recommend AMD's latest quad-core CPU.
The 3D graphics card market changes too rapidly for us to get bullish about a card with premature driver software. The ATI Radeon HD 3870 X2 shows promise, even outscoring Nvidia on many PC games, but we would still wait until AMD works out the kinks before handing over your $450.