You need to know now that mhz is not the only indicator chip performance anymore.
See Intel.com for a comparison of their Pentium 4M notebook chips (which are a version of the desktop Pentium 4) and should really only considered for desktop replacement notebooks (mostly plugged in all the time in one location).
The Pentium M (Centrino) chips are the ideal for most who do not need the hyperthreading (multitasking) element on the Pentium 4M's -- A Pentium M 715 1.5 mhz Dothan or above (higher number) with 2mb L2 system cache will perform 1.5-2x its mhz rating in comparison to a Pentium 4M. It will get 3.5-4 hours using wi-fi in most cases and up to 5 hours not using wi-fi. You are fortunate to get 2 hours or a bit more out of most Pentium 4M notbooks but some have huge batteries that can increase the battery life (but not decrease the weight).
Both Pentium 4M's and Pentium M Centrinos are 32 bit so the Athlon 64 (64 bit) is better prepared for Windows Longhorn 64 bit (to replace Windows XP and XP professional) likely in 2006 or 2007.
You can buy any of the 3 notebooks for the uses you mentioned but the Pentium M notebooks will be the thinnest and lightest for the LCD size you select and they will have the longest battery life (and use the least A/C current when plugged in).
Dedicated video memory (an ATI or Nvidia video card) is essential versus shared/integrated video memory (chip on motherboard only) if you will do any demanding games or video -- but if you want to go under 5.5 pounds you will only have the shared/integrated video option in most cases.
Keep in mind a new Centrino (Sonoma) specification is coming very soon (likely by March) which will have improved video and audio, a new chipset and a faster system bus and memory speed.
I've been looking at notebooks and see a lot of brands that feature Intel chip sets that clock at 3 Gigs or better, but when I shop Dell it seems most of their Pentium M machines clock in the mid 1 gig range. Does anyone know why this is, and if I should be concerned about buying a machine with a fast clock speed (and 800 FSB)?
I'd use this machine for office suite applications, communication, digital photography and limited gaming.

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