Chime in: When should you replace a PC instead of upgrading it?

[Windows Central]

When should you upgrade a PC instead of buying a new one?
The world of PC building is an expansive one, allowing you to pull apart your rig, remove or add a component or a few of them, and then put everything back together and enjoy a more powerful computing experience. But when should you upgrade? And when should you buy a whole new PC instead?

Full story from the WindowsCentral blog...