Here is how to do what you want on color and B+W:
Frame is in color - image within frame is B+W:
Assume you are working with B+W image in PS. When ready to add final frame do the following:
Image | Canvas Size command
Choose color from lower right corner of dialog
Make sure the size of the Width and Height dimensions are in Pixels
Frame is in B+W - image within is in color
Image | Canvas Size command
Choose B+W color from lower right corner of dialog.
PS calls the it "Canvas extension color"
See here for all sorts of Touches of color within B+W images and how to do:
http://www.thephotofinishes.com/corelColortouch2.htm
is just one of a whole series of tips/tutorials on getting to B+W and mixing with color in PS and PSP.
Hope this helpful