I've kept my Compaq K6-2+ 450MHz going constantly, almost 24/7, for.... I don't know... 3 years running now, almost? They get hot, but they're designed to withstand it. Do what the others said and take out your battery. Not only does the battery get damaged, but on mine at least, it gets hotter if the battery is in. Maybe this is just when the battery is charging though. Definitely set your LCD to turn off after like 5 minutes, those are often the first things to go on a laptop, and they have a definite expected lifetime!! (I think on the order of 10,000 hours... better ones are like 20,000 IIRC)