For the money, that's not a bad spec. Surprised you can't supply an OEM Windows licence if you're preinstalling it though.
I think it would possibly struggle a bit with a game like Medieval TW2 though. The CPU is roughly equivalent to my old Core 2 Quad Q6600 performance wise and that would run it but not well. While the game does have multi CPU support it doesn't do hyperthreading and it's pretty demanding if the unit sizes are high.
Now granted, I'm working at the higher end of gaming PCs (mine is more in the £1000 price range) and if most of the OPs games are relatively old then I'm sure they'll be fine. I'd just rather see a bit more horsepower in the CPU and GPU. That's not a bad little machine but it's never going to set the world alight (not that much else will at that budget).