You can install the MS core fonts by installing the msttcorefonts package. To do this, enable the “Universe” component of the repositories. This is done by default in Feisty. After you do that, use the following command from the command line:
$sudo apt-get install msttcorefonts
This will give you the core fonts, but if there are other TrueType fonts that you want installed, it is as easy as copying the font files to the ~/.fonts/ directory.
After installing new fonts, you will have to log out and log in again to be able to see and use the new fonts. If you want to avoid this, you can regenerate the fonts cache by issuing the following command:
$sudo fc-cache -fv