windows backup?

Winclone (+ more info, please)

So far, the only one I've found that works from OS X is Winclone. They now charge for it, but I think you can still find the free version depending on what OSs you have. Also, you have to be careful and read the instructions all the way through. If you don't you may find you've clobbered your backup to the point where it can't be salvaged.

If you're wanting to back up from Windows, however, most of the Windows backup programs work well enough. Some of them don't, because of the differences in architecture, so check them out first.

To get a more useful answer I think you'll have to state which OSs (and perhaps what machine) you use.