Lamp degrade over time, and a lamp failure is defined as reaching some level of output, I've seen 50% used. Of course all lamps won't degrade exactly the same so there is some sort of normal distribution. But if they guarentee 1000 hours, that probably means that more than 90% of the lamps will have more than 50% of light output after 1000 hours. You could probably expect to use it another 200-500 hours before you actually had a hard failure where you had no light output. I saw dell is selling the bulbs for only $459. I think I will buy a new projector at that price.