Can someone help me in getting a hang of the mobile processors?
What's the difference among pentium M, Centrino and so
And what makes them different from the desktop processors except for the fact that they are smaller in size and are used in laptops?
Don't bother with either of those, and try to get a Core 2 Duo or a Core Duo mobile processor. They will run much faster than a Pentium M or a Centrino.
A general rule of thumb that I have heard is that a Pentium Mobile will perform similarily to a P4 s478 at twice it's frequency. For example, if you have a Pentium Mobile @ 1.4GHz, expect performance along the lines of a gimped P4 Northwood @ 2.8GHz. Of course, the lower L2/L1 Cache will make the estimate be heavily off. Unfortunately, the mobile processors also run at a variable voltage and frequency to conserve battery power. This means that the processor usage rating that Windows will give you is usually off by large amounts. Other than that, there are not too many differences. They both operate generally the same way, and some ms478 CPUs can run in desktop boards (though they are usually costly due to the custom chipset requirements)