With the increased emphasis on disk images in OS X, you may want to tweak the preferences for Disk Copy. By default, Disk Copy verifies the checksum on all disk images as it mounts them. This takes a bit of time, and can become annoying if you're installing a large number of programs.
To prevent this from happening, launch Disk Copy by double-clicking (in /Applications/Utilities). Open the preferences, and in the 'Verifying' tab, remove the checkmark from "Verify Checksums". Now when you mount an image file, it will happen quite quickly.
Mild caution: This theoretically means that you could attempt to mount a 'bad' disk image that would not normally pass the verification check. I admit that I do not know what implications this could have on your system. I just know that I've been running it this way for quite a while with no negative side effects, and I love the speedy disk image mounting.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20011102233306578