Source: PlanetHalfLife

IGN: Gear has put online a great and detailed article that compares the different versions of DirectX with Half-Life 2. Here some words:

While anyone reading this article is sure to have a newer card than a TNT, there are still plenty of people currently running the game on a GeForce 4, RADEON 8500 or any number of other aging cards. We see mail everyday wondering how well the game will look on these older cards, or if someone with a GeForce FX 5900 should pick up a cheap RADEON 9600 Pro to run the game in DirectX 9.0, even if the framerate difference will be negligible over the 5900's DirectX 8.1 rendering.

This article is for you folks. If you're wondering what graphical features you're missing out on, or would like to see how much better your X800 XT looks than someone's 8500, read on. We've taken a boatload of screenshots to compare the four main rendering types, DirectX 7.0, DirectX 8.0, DirectX 8.1 and DirectX 9.0, and put them side-by-side for your viewing pleasure.

A great article, which can really help you picking out a new Graphics Card. You can read the full article here at IGN: Gear.