A slow computer is usually not worn out - it's clogged. Years of installed programs, browser add-ons and things quietly starting up in the background. Clearing that out often makes a machine feel years younger.
If you've had a scary pop-up or a phone call claiming to be "Microsoft", please don't act on it - just call us. We'll check whether anything actually got in, remove it if so, and show you how to spot the next one.