Digital BW, The Print

Here's another way

1. Create an hue-saturation adjustment layer in Photoshop CS. You 
just leave the blending mode at normal.
2. Select "master" and bring saturation down to -100.
3. Select the individual colour channels and adjust the "lightness" 
to your liking.

What I like about this technique is that it's intuitive. When you 
select the "reds", for example, and increase the "lightness", the 
reds get lighter.