Can I upgrade my processor to make my system faster?

In reality, yes you can. However getting the correct processor to fit your system board may prove difficult.

When your system is new, the mainboard can take a range of processor speeds, and these will be readily available. Three or four years down the track when you want to improve the speed of your system, these processors will probably be unavailable.

It is more common to upgrade the mainboard, processor and memory together, as the new processors on the market probably won't physically fit into you system board. Also the memory will probably be different, and this needs to match the system board.