how to convert an image to a monochrome bitmap?

hello,
I have to convert a CMYK image into a monochrome bitmap and I can't figure out how to do this in Photoshop.
In the menu under image - mode , there is only greyscale option, or if I choose bitmap, there is also no monochrome option.
Does anybody know how to do this?
Thanks!
quaqualita

I'd just export it as a GIF and limit the colors to 2 colors.

does this work dek ?.. can't you just change it to rgb color and do the stuff you want.. and then change to cmyk or whatever again later on ?

hi,
first of all thanks for your quick replies.
problem is, the printing service this image has to go to, insists on a monochrome bmp ( I really don't know why, but hey, what the client wants, he gets, right?) - not a gif and not in RGB.
It has to be a 'real' monochrome bitmap, meaning that each pixel is represented by a single bit.
So, I'm still not sure, if and yes how I can convert my image into monochrome in Photoshop.

can't you change from RGB to monochrom tho? *goes to open adobe*

hi,
if you can tell me how? Maybe I'm totally stupid now, but I can't find an option in Photoshop where to convert from RBG to monochrome.

image>>mode>>indexed>>choose 2 colors ... i think