Thinking of getting SSD for old system.

Hey guys, Like the title says, I'm thinking of getting a solid state drive for my 5-6 years old PC. Now, there are slight problems along with it, for example, there is a bit of stutter while watching videos and playing video games. While watching videos, there's no stutter if the image is still (Like some dude talking sitting at a desk) but it does stutter if it's like a plane flying over a...