User:Mardus/Free software support of older operating systems

Free software applications support older operating systems for much longer than proprietary applications.

Timeline

 * Operating systems:
 * Bar stops at extended support end-date.
 * All operating systems are assumed to have the latest service packs and update rollups.
 * Mozilla and Firefox are usable since version 0.8. This is just an approximation, because:
 * Mozilla became stable by version 0.8, and
 * Firefox (then Phoenix) was more or less usable for simple browsing from version 0.5.