All I plan on doing on it is chat rooms (I like talking to strangers sometimes randomly), watching download movies only (never any streaming or anything), probably reading the occasional free comic book and that’s probably literally it. So how old, crappy and cheap can i go if I’m only doing these 3 things?
The plastic Core 2 Duo MacBooks can handle 720p movies. The unibody MacBook Pro can probably do 1080p, but the screen is only 720p so it doesn’t really matter. Not sure how well El Capitan and older is going to support your chat rooms though.