Hey, your poll just has 2 ptions for DIY Advice, you might want to edit the post and make one yes and one no. I believe the Celeron is going to have a MB with a lower fsb, so even if you swap out the chips, you aren't going to have the full impact of the P-M. Not to say there won't be one, it will probably feel like a lot, it is just something else you may want to check.
This is your CPU checklist in order of doability:
1. Do the sockets & pins match.
2. Check the mainboard chipset, make sure it is compatable with the upgrading CPU.
3. Check the voltage of both CPUs and make sure they fall within spec's.
4. Make sure the BIOS will recognize the chip (if there are other models using the chip you want ot move to is a good indicator)
When you are doing the swap, have either thermal tape or AS5 on hand.
-Take off the heat sink and use a utility blad to scrape off the factory applied thermal tape.
-Clean the area with rubbing alcohol or another solent to remove all the goo. (To be a real maniac lap the heat sink to make it oerfecftly flat.)
-Clean the top of the CPU once it is in to remove oils from your hands and other contaminents.
-Apply the AS5 or thermal tape to the CPU (you may have a single heat sink that hits several chipsets, so make sure you replace all the thermal tape on those too.) and re-attach the heat sink.