Regular on the forums know that I really like Logos 4. But now, thanks to the generosity of Dominic, I've been able to upgrade to a much faster graphics card and a surprisingly cheap 1920x1080 LED display. It's made an enormous difference to both the speed and clarity of Logos 4, and I'd thorough recommend those considering an upgrade to think about something similar.
Do check your PC is fully compatible with a game-spec graphics card. My power supply wasn't, so I had to budget for a new PSU.