Need tips on upgrading my computer?

Okay, so I have a Dell Inspiron 1150, and it's a good ol' laptop. It works fast, it has good quality all around. There's just 1 problem with it, it has little memory. It has so little memory, that by just watching a Youtube video, my CPU usage goes all the way up, lagging the whole thing. I cannot take much media reaction from websites, including games as well. I was going to buy a 30$ memory upgrade for this laptop, but a man at Radio Shack said I would just have to get a new computer. So what should I do? Can I even get a memory upgrade for this old computer? Or should I get a RAM upgrade? Answer all questions if you can. TQ!