Which games do you own but can't you actually run (as well as you'd like - at least!)
Earlier this year, I picked-up Need for Speed: The Run via a stack of Coke Zone points - but try as I might it's just not going to run properly on this PC.
It's almost a hobby I've developed - seeing if I can get it to work better from time-to-time - but I think I've about rinsed my options...
My take is that it NEEDS more than 2 Cores - my CPU (Athlon2 x2) is at 100% pretty-much constantly wheras my GPU runs at low utilisation even with some settings turned-up above 'Recommended' - and it's not better with everything on 'Low' so I'm fairly sure it's CPU-bound.
In fact I'd go further and say it's probably a PhysX issue - Shift and Shift 2 had similar problems which were solved, eventually, by updating PhysX. Not having a high-end nVidia GPU means it's loading all the work on the CPU I guess??
It remains the only game I've tried on this PC which doesn't work well enough to be really playable - because it's hard to control a car on a nice drift when your FPS is leaping from 15 to 30 and back!!
So - what games do you lot have which won't run as well as you'd like - what games have you sidelined for your 'next PC' - what games lied particularly egregiously on their Requirements?? :)