Even if you use OpenOffice, you might still want all the Microsoft fonts so that documents created using Word or PowerPoint look as they were supposed to when you open them with OpenOffice. You can install the MS core fonts by installing the msttcorefonts package:
Note: You need “universe” in your sources.list
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.