Can I switch an Intel celeron M processor with a pentium?

Answer 1

You can replace most celerons with a "flip chip" which is basically a PIII chip the same size and shape of the celeron. Before doing so make sure that your socket can handle the replacement plus that your motherboard can be clocked at a higher speed. Celeons usually run at 66 mhz whereas you need 100 mhz for the PIII.

Answer 2

No, because the slots will be different.