Laptop CPU's got me baffled
 

Ok, this ongoing laptop search, there are so many damned CPU's and I can make no sense of them. Why would I pay considerably more for a Pentium M 1.3 ghz than I would for a P4 2.80 ghz. Doesn't seem to make sense...
So far I've come across,

Pentium
Pentium M
P4-M
Centrino
Celeron

Original intent was a P4 2.80 or thereabouts, I'm baffled by all the rest of this stuff - anyone help?

Thanks

my best guess-

Pentium=pentium III

Pentium M=mobile pentium III

P4-M=mobile pentium 4

Centrino=saw this on an advert on the telly, apparentley you can use your lappie at the top of a mountain, they forgot to mention you need to be within 100m of a wireless access point :D

Celeron:pentium II

Click for more info... http://digilander.libero.it/fiz/files/Pentium.wav

basically an 'M' CPu is a mobile wot ever it says, thus meaning cooler and better of battery life.

Celerys are pants end of story.

Centrino is a mobile cpu with wireless - centrino being the name of the combined technology.

Also, a centrino based machine, with the mobile cpu is more power full than a normal P4, thus meaning one running @ say 1.6ghz is in fact as powerfull as a 2.0ghz+ P4.

Much like the AMD cpus, they are more efficiant..
Hope that makes sense, ones almost asleep

Thanks chaps, helped a lot.