^ everyone overbuys for a good reason. Too much, at worst you've wasted a few dollars, very fee considering how cheap ram is now. But if you ever skip and end up using more, its the fastest way to turn any PC into a total slug. I have seen some Windows machines kick up more then 4GBs, and remember windows spreads its bloat in a way that makes use of more ram even when its not 'in use' Linux doesn't need/use that to the same extent but remeber things like ZFS will use that ability. As well, when using multiple large VMs I can kick up 4-5GBs, it's not actually in use but I need the space so I can make sure I don't run out on any of the OSes. For an old computer, sure, 512-1GB is fine. Heck, my raspi is more then decent with 512. But for new DDR3 conputers, when 8GBs costs ~$35 theres no reason not to overbuy.
@OP- try Lubuntu or Xubuntu