Kimi, Adobe Camera Raw doesn't use Actions (.atn) files, it uses presets.
Basically, all the preset does is adjust the sliders you encounter when you open an image in ACR. Actions, on the other hand, work in the regular CS3 editor, and they sequentially apply a bunch of steps to your photo to achieve an effect. Actions can be much more complicated, involving layers, filters, curves, levels, etc.
The ACR presets are installed in a different folder from your Photoshop actions.
Basically, all the preset does is adjust the sliders you encounter when you open an image in ACR. Actions, on the other hand, work in the regular CS3 editor, and they sequentially apply a bunch of steps to your photo to achieve an effect. Actions can be much more complicated, involving layers, filters, curves, levels, etc.
The ACR presets are installed in a different folder from your Photoshop actions.