Use the LDraw All-In-One-Installer, in short AIOI, if you want a quick and easy way to install LDraw parts library and many of the popular 3rd party tools as well. The details of the installation process are listed below.
The AIOI supports Windows XP (Home and Pro), Windows Vista (all versions) and Windows 7 (all versions). On 64-Bit Operating Systems it will install in the "Program files (x86)" folder. The Installer will NOT run on Windows 95, 98, ME, NT Ver 4, 2000, or XP below SP2.
You can download the AIOI by going to the download database under the heading Critical Files and Libraries.