Which notebook is preferable is really dependent on your intended use. If you are basically looking for a notebook for internet browsing and word documents the Dell 6000 is a very good choice and will give you a lot of battery life.
However, if you intend to do video editing, disc burning, or other heavy duty tasks, stick with the zv6000 or the CompaqR4000(almost identical to the HP, but less money. Be sure to upgrade the video card to 128mb since that upgrade will also get you a firewire port, a 6 in 1 card reader, and an Express 54 slot (about a $25 upgrade). The brightview (glossy) screen also produces a beautiful color rich picture and I'd highly recommend it as long as you wouldn't mind a bit of glare from reflection.)
The other advantage of the Athlon is that it will be compatible with the new 64 bit version of Windows that will soon be released.
So, if you are not interested in 64 bit, if your main concern is battery life and you do not mind trading off some performance (speed) than the Dell 6000 would be OK.
Since I plan to do a lot of photo and video editing, I went with the Athlon. So far so good, although since it just arrived, I've not had a chance to really put it to the test. Battery life was definitely non-stellar. About 2 hours - routine tasks and watching a movie.