In Windows, if you want to change the program that is used when you double-click a file, you would need to dig into Control Panel’s Folder Options applet. This is the case of one of those illogical steps Microsoft users memorized becuase of its consistency across all Windows platforms. However, this more logical location in Ubuntu threw me off…
Figure 1: Ubuntu's "Open With" dialog. Click the application you want to open this type with.
Right-click on a file of the type you would like to modify, and click Properties. Click the “Open With” tab. Figure 1 is what it should look like. If the program you want to use is in the list, click the option button next to it and click Close. If it isn’t, you will need to add it by pressing the Add button. A screen looking roughly like Figure 2 will pop up.
Figure 2: Ubuntu's Add dialog within the Open With box. Select the application you want.
In this window, click the name of the application you would like to use to open that type of file with, and then click Add. You will be brought back to the window shown in Figure 1, except the program you selected will be added to the list.
Ubuntu is nice; many of the bumps I’ve hit have only been because of my un-learning of the Windows way.