Buying a prebuilt PC is a bad idea. First off, Prebuilt PCs are more expensive. Second, they often come with only a few opportunities for upgrades beyond adding more RAM and changing the graphics card. Third, they are often times loaded with all kinds of bloatware and weird drivers that neither you nor your computer really need.

On the contrary, building your own PC is cheaper and gives you the ability to pick out the parts yourself, which allows you to extend the potential lifetime of the PC. There are only two drawbacks to this method: 1) you must BUY your OS separately, just like the good ol' days, and 2) the setup process might take a little time.