The first question that needs to be answered is which of these two sub-$200 graphics cards delivers the best performance? But if you watched closely as went through each one of our gaming application tests, it's going to be a hard call to make.
Lets take a quick look at the 1680x1050 performance...
As you can see, based on the seven games we tested using a number of various quality settings, the performance difference between the Radeon HD 3870 and GeForce 9600 GT worked out to be very small. Each product had its ups and downs and on average the 9600 GT turned out to be less than 1% slower than the Radeon HD 3870. Those wanting to use AA/AF exclusively should note that the 9600 GT appeared to be slightly better when using these quality settings.
Another interesting point worth noting is that adding a second graphics card did not give either product a distinct advantage, at least in Windows Vista 64-bit that was our platform of choice. We found that if the 9600 GT, for example, was faster in single card mode, it was also faster when tested using SLI. Again, while the results did vary over the 7 games tested, the average performance received from each card was very much the same, which is amazing considering how different their designs and architectures are.
Given this scenario we believe that other factors will become more relevant when deciding what card to buy. If you come across a good deal for either product, depending on where you are located, this could be the number one factor to consider. In the US, there is a $10-$20 gap separating these two products, with the Radeon HD 3870 being the more expensive option.
An advantage we have seen in the reference design Radeon HD 3870 cards is the better cooling offered, which despite of being dual slot, it is much quieter and cooler than the single slot cooler of the 9600 GT. However, already we have seen a number of manufacturers moving away from the reference Nvidia cooler by offering their own enhanced solutions, and many are doing so without a price premium, so watch out for that!
You may also want to have a clear upgrade path using SLI or Crossfire, so if a few months from now you want to grab a second card at a discount price (we hope in the $100-150 range), you should buy according to the platform you are currently running as we don't see huge advantages in SLI vs. Crossfire.
If for a moment you are thinking this is becoming too complicated, well don't. Six months ago we did not have such compelling, great performers in this price range, now we have two! If you can spend a little bit more for a GeForce 8800 GT, that is perhaps the sweet spot to be at, but if you don't, you won't regret for a second buying the GeForce 9600 GT or the Radeon HD 3870 at such attractive prices.