Upgrading MY PC

I have sometimes a problem with my computer. Sometimes it is just processing so slow even my local area connection speed is already 100 Mbps. I don't know exactly what is the problem..or maybe my computer is already old. It might also be that my computer memory is almost full. I don't know but my sister who is an IT specialist told me that my computer memory might be full which results to slow speed. She mentioned to buy memory for my computer. Buy are selling memory for computer. I will see if I can get one.. I guess $40.00 till $100.00 is not too bad compared to buying a new PC..What do you think?? see you tomorrow again!! Have a stress-free weekend!!