Proview 15" CRT: This little guy lasted around 7 years. Even got a little sentimental when I sold it to scrap shop a few months back
LG W2043T 20" (1600*900): It has been 8 years and counting for this one. The resolution is still adequate for me and I am not going to replace this monitor till it dies as it has best colors I've seen in a budget LCD.