Download it and see for yourself ^^ .

The tool is capable of emulation several DirectX9 functions and some other functions. It also possible to change the ID's of your graphics card so the program will think you're running an nVidia GeForce instead of an ATi Radeon or so. There are some more functions but you'll see it when running the program.

All those features might prove useful when trying to run new games / applications on old graphic cards. That includes 3dfx cards.

The changes made with the program are only applied to the selected executable. In other words: The tool is not monkeying around with your drivers and/or software. Even no modifications to the selected executable.