If your motherboard has both slots for the CPU, it is better for you to try both of them. Do not put both processors in because Older model motherbards do not have a dual boot function.
One of them may seem like the obvious choice but it is up to you how dependent you are on the processor and what you mostly use it for.
Each processor has L1 and a L2 cache
With Pentium II the L2 Cache is 256KB
With the celeron the L2 Cache is 128KB
It is all based on how you will use the computer.
Also referred to as secondary cache, L2 Cache is a small amount of high-speed memory located close to, and sometimes on, the CPU. L2 Cache allows for high-speed access to the system's most commonly accessed data. On newer CPU's the L2 Cache is most often located directly on the CPU, allowing for higher performance.
I say try about a month for each processor and see what works for you.
** processor is not as important as RAM** With adaquet RAM, the processor will hardly seem any diffrent
