New
#11
4GB should be enough for a smooth w10 experience imho. Adding more ram never hurts though.
QFT
Inexpensive 120 GB SSD for main OS, and HDD for data is without doubt the best thing for any PC, old and new. It makes a 7 years PC look like a current one in my experience (my netbook for example :) ). And a SSD can be reused in future computers unlike RAM (if previous generation) or CPU.