I have an archos Jukebox 10gig and it is probably the worst of the HD based mp3 players, the batteries still get 8-10 hours of play and it has worked everyday, but it freezes a lot and I can't even walk to school with it in my back pocket without it freezing and me having to restart it, you have to use the alternative software with it because the stock software sucks, with that said, if it sits in the backpack you could wal all day and it won't skip.
If I was to buy again I would purchase an iPod, I love the instant on features and the interface is the best I have ever seen. I would also consider the dell, although I am optimistic that apple's 4g ipod will have better batteries, of course, apple is known as being a little bull headed.