Battery Life = 4-6 hours for gaming; 4-5 hours for movies. (The PSP 3000 is the upcoming model of the PSP; I don't know the release date off-hand.) Beyond that, I have a hard time making recommendations for kids aged 4-6. My natural inclination would be to recommend the Nintendo DS, since I would expect it to have more 'age appropriate' games (ie., the kind of licensed stuff I wouldn't touch: Hannah Montana, Spongebob, etc.). I don't think battery life is as major a concern for the DS as it is the PSP. That said, the DS doesn't play movies, so there are some drawbacks as well. I would take a serious look at what games / movies are out there that you would buy for your kids before deciding. What They Play would be a good starting point for you; the site's founder used to be an editor for Electronics Gaming Monthly. (Note: Nintendo, in the past week, announced an updated revision to the DS: The DSi will have larger screens,two low-grade digital cameras, built-in web browsing, and is replacing the GBA cartridge slot with an SD card input. It's also not coming out in the U.S. until April 09 at the earliest, so feel free to ignore all the news stories you see about it.)