Windows 7 supports DirectX 10 & 10.1 Graphic features.

The new version of Microsoft OS - Windows 7, will support full software rendering of DirectX 10 and 10.1 features.But you will have to upgrade your graphics card to play DirectX 10 and 10.1 games.
Windows 7 Graphics Feature-

• will support full software rendering of DirectX 10 and 10.1 features.
• WARP 10 [Windows Advanced Rasterization Platform.]-WARP10 is a new component that will be part of DirectX graphics technology in Windows 7.
• You can even use 8x multi-sampled antialiasing, anisotropic filtering and all optional texture formats.