There are no such thing as a socket adapter.
If you want to upgrade the CPU, then you need to find a faster Socket P 478 CPU for your laptop. However, it is not as simple as that. You need to make sure the current CPU is not soldered into the motherboard. Next you need to find out if the more powerful Socket P 478 CPU is compatible with your laptop. You can either call Dell or use Google to find out what was the fastest CPU Dell offered for that specific laptop.
If you install a CPU that the BIOS cannot recognize, then you will not be able to use the laptop at all.