I upgraded an old 1.5Ghz Celeron to a 2.2Ghz Core 2 Duo in my old media laptop. The difference was quite remarkable, both in speed and temperatures (the wonders a layer of thermal paste makes).
To be perfectly sure which socket your laptop has, look for the product specifications online. SKT P is much more common than SKT M, although you should still be able to find CPUs for both. Just make sure that they both use similar voltages and have a similar thermal ratings. If you need further help knowing which CPUs are compatible, you can always email customer support. Packard Bell were helpful in suggesting which could work, but they couldn't advise me in taking the laptop apart for the upgrade because "their technical manual is confidential". Fair enough - I just worked it out for myself.
To get a good idea what can be done, you can always try looking online for variations of your laptop model. For example, my laptop was a PB EasyNote SB007, but i found SB009 and NB014 models that were very similar except for the CPU/RAM configurations they had. That helps you know which parts are officially supported for your laptop.
Finally, check for BIOS updates for your laptop. Quite often certain newer CPUs won't be supported without having the latest version of BIOS. Check change logs for details.