.dmg.sit file

A .sit file is a file that has been compressed using Stuffit.
A .dmg file is a file that is an exact image of the disk that contained it. For instance, if I wanted to create a CD that contained a number of folders and files and wanted to ensure that everyone who opened it saw it in exactly the way that I created it, I would create an image file which, by default, would have a file extension of .dmg If I compress this file to make it easier to send, it would end up with .dmg and .sit.
To install these you need to:
1. Decompress the file using Stuffit Expander. This is available from the Allume web site. Just put Stuffit Expander into Google and go from there. All you need is the FREE Expander. Follow the instructions for downloading.
Once it is installed, you can decompress the sit file. However, for some reason your system associates QuickTime with .sit files and this needs to be changed.
Control + Click the file and choose Get Info. In the Get Info window you will see the name of the application that normally would open this type of file. your probably says QuickTime. Click the drop down arrow and choose Other. Browse for Stuffit Expander and choose it. Then, in the section that asks if you want to open all files like this, in this way, click Yes.

Once the file is decompressed you will be left with a DMG file which you double click. It will mount a disk looking icon on the desk top which you treat like a CD. Open it and follow the instructions, or, if there are none, drag the contents to the HD.
Close the folder and drag that icon to the trash. It is ejected.

Sounds complicated by you only do this once. Next time it is automatic.

Let us know how you get on

P