The LG LCD monitors I installed in San Francisco Airport in summer 2007 are still all working fine after 5.5 years at 24 hours per day. After about a year maybe, we did replace a board in each one due to a factory recall, so I guess I can only count 4.5 years at 24 hours per day with no problems.
Their convergence, corner focus, and color temperature/balance are all still flawless as well.
