Hard drives in desktops have about a 7 year Mean Time Between Failures, about 4 years for laptops. If your computer is working well, but older, having the drive cloned (duplicated) so it boots properly allows you to add a larger drive and helps protect you from drive failure. It also gives you more storage space. Most cloning software requires you to use a larger drive for the clone. Cloning software is available free, just can't recall the name right now, but it's easy to find online.
The other common failure over the years is the power supply. Dells use pretty cheap parts, and I have had to replace several of their power supplies. It takes a few minutes. The most common sign of power supply problems is the computer shuts down on its own, usually crashing out, not an orderly shutdown. With some setups, it will crash and reboot continually. The last problem is fatal, that happens if the capacitors dry out, and it just won't operate. It tries to boot (or not) This can happen with heat or even lack of use.
Most of my multiple computers are refurbished, and I clone and replace the hard drives right away. You can get refurbished computers pretty cheap with small hard drives, put in a clone and keep the old hard drive, or use it for an occasional backup, so if the new drive fails, I still have access to the Windows licensed OS. Replacing the mother board means your OS license is void.
Large hard drives are not all that expensive anymore, but buy a premium brand and model. They do seem to last longer. You also have to make sure the drive is the correct type for your computer, but your friend will know.
The more I do, the less I accomplish.