You want any decent Pentium M (Centrino) notebook for 3.5-4 hours at least using wi-fi 100% of the time and up to 5 hours with wi-fi turned off. All you can expect with a Pentium 4M cpu is much more heat, battery life likely 2.5 hours and under (depending on LCD size) and also more weight and notebook thickness.
Specify the LCD size you want. If you want a 15.4" widescreen at 6.5 pounds like I have check out the HPZT3000 and/or Compaq X1000 series at X1000forums.com and hpshopping.com
If you can do without dedicated video memory that the above has (necessary for any robust games and higher end video programs) consider the HPDV1000 which is a 14" widescreen at 5.3 pounds. It runs DVD's and CD's with the notebook turned off and has a remote control built into the PCMCIA slot (pops out).
Both of these use the Pentium M (Centrino) processors. Get at least the Dothan 1.6 Pentium M 725 or higher for the 2mb L2 system cache (lower models only have 1mb)
I'm shopping notebooks and need one with a long battery life--at least 3 hours. I've enjoyed my compaq 1700 (until i dropped it and broke the lcd) and looking for a laptop with
at least 2.6 gz speed
p-4 or better
512 ram
40 or more gig hd
under 8 pounds
reliability.
I sometimes work outdoors...what's the best desiplay to look for? Price up to 1800.
Thanks in advance.

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