Depends exactly what you’re doing on that old PC.
If you just need to connect for administration and the like, VNC is decent. It’s my default.
If you want to watch videos or the like, I’d definitely suggest Sunlight and Moonlight. It’s a streaming remote desktop that’s meant for streaming gaming, and so it’s really good at video and audio.


To be fair, and this is coming to someone who is fully sold on LibreOffice and hosts Collabera, the two word processors can open each other’s documents, but cannot produce identical outputs for the same files.
For 99.99% of things switching between the two is going to be just fine, but every once in awhile that 0.01% will really bite you, especially if it is something important such as equations which I have seen first hand don’t properly migrate to LibreOffice.