If you are using Google fonts I would suggest the following.
If you want the fonts to run from your localhost or server you need to download the files.
Instead of downloading the ttf packages in the download links, use the live link they provide, for example:
http://fonts.googleapis.com/css?family=Source+Sans+Pro:300,400,600,300italic,400italic,600italic
Paste the URL in your browser and you should get a font-face declaration similar to the first answer.
Open the URLs provided, download and rename the files.
Stick the updated font-face declarations with relative paths to the woff files in your CSS, and you are done.