Here's a simple but great B&W conversion method.

1. Open the photo you want to convert.
2. Click Layer >New Adjustment Layer >Hue/Saturation and choose Color as the mode in the pop-up dialog box.
3. Click Okay.
4. Click Layer >New Adjustment Layer >Hue/Saturation and leave the mode as Normal.
5. Drag the Saturation slider completely to left. Click Okay.
6. Now go to the Layers palette and click on the middle layer. This is the Color H/S adjustment layer.
7. Drag the Hue slider across until you achieve a look you like.
8. Click Layer >Flatten Image when you are satisfied with your results.
9. Click Save As and choose a file name. :)