After Mac 10.5 release I couldn't use DMGextractor to extract .dmg file to iso file.
Actually I can extractor .dmg file and got iso file, but when i use

mount -t hfsplus -o loop /directory/location_of_iso.iso /mnt/mountpoint

got error message like
wrong fs type......


But I found HFSexplore could read .dmg file directly under windows.
You can download from [url]http:///catacombae/index2.html.[/url]

much easier than use dmgextractor to convert to iso then read file.