You might want to read this excerpt from a review.
http://www.amazon.com/gp/product/customer-reviews/B000301N94/104-2928874-5223903
I immediately wanted to try some of the latest games on the market (e.g., Half Life 2). I bought the game, loaded it, and quickly found out the computer wouldn't play it. After many painful and unhelpful "run-arounds" with Sony and Intel non-support, I learned that many of today's games require a technology built into the hardware of the graphics controller. The PCV-RS720G computer with its "integrated graphics" doesn't support that hardware technology. So the games won't run. (NOTE: For those that care, it is called Hardware Transform and Lighting. The 720G's integrated solution performs T&L in software, which many games do not support.)
But never fear...I am a clever guy...I bought the PC because it had the ability to expand video capabilities via the PCI-E slot. RIGHT?...Well, this is only partly true. Sure, there is a slot for an upgraded video card that will support the new games. BUT (and this is a big BUT) PCI-E cards require at least 300W power and typically 350-450W. Low-and-behold, the SONY only comes with 295W power supply (PSU).
Well, I just need to swap out the PSU, right? Wrong! It turns out, to my great chagrin, that not only will replacing the PSU void my warranty but also no 350W PSU exists on the market that will fit into the case. Turns out (and this is not a Sony-Only thing) that Sony had a PSU specially built so it fit snuggly in their VAIO cases. The PSUs are completely different dimensions than standard PSUs. Due to the space in the case, you can't even rig a standard PSU to fit.