I'm currently browsing on my loyal 2009 toaster, but I feel like buying a new, better computer. Not top of the line per se, but one that can run some decent games, with a fair price-quality comparison.

I'm no computer wiz, so can someone out there explain me what things/qualifications I should pay attention to when buying a new computer? A short explanation on how I can switch hard drives would be nice too, as I want to keep my old harddrive when switching computers.