The best way to do install your new fonts on your
Windows-based computer, and to be sure that all programs have proper access to
them, is to:
Open the control panel
Click the FONT icon
On the font window that opens up, click FILE and select INSTALL NEW FONT.
Next, navigate to where you downloaded the new font to. I normally download them to my desktop, which on my machine is C:\windows\desktop.
Highlight the font(s) to be installed, click the COPY FONTS TO FONT FOLDER box and then click INSTALL.
Now you can delete the original files from your desktop - that's why you clicked the box to copy the files to the folder in the previous step.
That's it. Your new fonts will now be available for use.
If you just move the new fonts into the font
folder, they won't necessarily be available for use in all programs because they
aren't added to the Windows system registry that way. An exception is if you
move the new fonts using Windows Explorer since my understanding is that it'll
automatically do a quick & dirty installation when it sees you moving a font
to the font folder.