Need more space...for PC not the kitchen!

I have often been getting errors regarding system memory on this laptop. It's frustrating since the browser shuts down while I'm in the middle of writing. It is also annoying that I can't use  other programs simultaneously. On the other hand, it has helped me prioritize which I should do first so I can finish one work than go "alt-tabbing" on different things.  The hubby promised he'd do something about this but he has been so busy with work and hubby (RCs) that I am extending my patience..it's a virtue after all!