Game Unplayable

[Barman1942]

PC Specs

8GB DDR3 ram
Phenom X4 955 3.2ghz
Radeon HD5770

I just bought the game today during the Steam sales after seeing all the patches that have come out for it. I left graphics on medium, set up my joystick and went to play. Only when the level finally loaded, I was getting graphical glitches everywhere, the game was a slideshow and my plane wasn't responding at all to my joystick, I just had a mouse cursor. Any help here?

Screenshot of the graphical glitches.