with a full blown P4, you will get about 2 hours at best of battery life. also, the lappy will get rather hot. when I first started looking for a lappy, I wanted to get one for around $600 USD, but it turned out that that was not feasable, all that was available were the crappy regular celerons. I ended up spending $900 on my lappy, but a celeron M will get you roughly 3 hours of battery time.look at the cache when you look at the celeron M, make sure ir has 512kb or more