Some hardware vendors now ship systems with Linux pre-installed. Some distributions can still be installed via anonymous FTP from various Linux archive sites, but in many cases, the size of the distribution makes this impractical. There are also a large number of releases which are distributed less globally that suit special local and national needs. The latest stable release is 0.98.3. Work has been progressing on an emulator for Microsoft Windows binaries.
Some companies have commercial software available.
How to Find a Particular Application. Look first in the Linux Software Map. Freshmeat is basically a site index that continuously updates the notices of new or upgraded software for Linux, and maintains indexes of the announcements and links to their URL's. The directory listings files can be very large, however, making them unwieldy for quick searches. If it's a large package that may require some porting, post a message to comp.os.linux.development.apps .