The .dmg file is the form in which your application, in this case FrontRow, travels around the internet. It is a compressed version of a Disk Image. A Disk Image is exactly what it sounds like and allows everyone to see exactly the same files and folders, right down to the placement of icons, as were on the original.
Once the .dmg file arrives at your machine, it is processed and the result is the Portable disk-drive you mentioned. This is the actual disk image. You obviously have discovered that by opening the disk image you have access to the installer or the files as required.
Once the installation is complete, you can safely delete the two files.
Enjoy your Mac
P
I am not sure what to do with a file (frontrow update) left on my desktop after it was installed.
There is on icon that looks like a portable disk-drive and the other looks like a regular file with the folloinwg name: Frontrowupdate1.3.Dmg
Is it safe to delete it or should I leave it on my desktop?

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