Is this worth me doing

Hi, I have an early 2009 imac 24 inch.

It's got to the point for about 5 years of no longer upgrading. I've just come across this and wondered if it's worth doing and how to do it

I use it for web surfing, editing documents, streaming, occasional designing.

I have the data backed up so can I install the patcher on the imac itself and run it? Would someone be able to talk me through it like I'm 5? I am considering replacing with a mac mini but this seems a free option instead for what I want it for.

Any help appreciated