Just thought I'd add a little real-world experience to this thread. I took delivery of my new laptop last week. The specs are:

Dell Latitude D610
Pentium M @ 2.0GHZ (533FSB and 2MB Cache)
1024MB DDR2-533MHZ RAM
80GB 5400RPM HD
64MB ATI Radeon X300 PCI-E Graphics
14.1" SXGA Display (1400x1050)
Integrated Intel 802.11g
Integrated 56K Modem
Integrated 10/100 Ethernet
Sony 8X DVD Burner
4 x USB2.0 Ports
Windows XP Pro SP2
3-Year Next Business Day Onsite Service + CompleteCare

In real-world usage, here are some observation:

Screen at mid-brightness, wireless LAN on, wired off, using separate USB mouse, surfing the net. About 4 hours battery life.

Screen at max-brightness, wireless LAN on, wired off, using separate USB mouse, playing GTA VC. About 1.5 hours battery life.

Screen at minimal brightness, wireless LAN on, wired off, using touchpad, surfing the net. About 4.5 hours battery life.

It uses a 6-cell battery. It's branded as a 53whr battery, so in real life it does come close. I also got the 90W charger instead of the standard 65W. The laptop recharges in exactly 50 minutes when off, or 85 minutes when on.

So far, I have only good things to say about this beast. I would recommend going for a Pentium M-based system anytime. Mine is a Dothan based on the 90nm process.