Piknik (sp? I can't see the above post!) yes, that's what I was thinking of. I access it from Flickr but I didn't know you could access it separately.
It's worth remembering that the best B&W conversion are not simple greyscale conversions, which can come out looking quite flat and dull. I'm sure how piknik does it but you may find it has a better result than just converting it in e.g. paint.
Incidentally, GIMP is an open source (i.e free) photo editing programme that has many of the same features as photoshop. It will have a bit of a learning curve so may not be appropriate for this but may well be good for the future?