I just got around yo buying this game a couple of days ago and I'm having the same issues. I've downloaded both patches and still nothing. I've tried several compatability modes and nothing. My setup is pretty similar to the one detailed above
amd 940 quad core black edition.
ati radeoan 4870 1gb video card
gigabyte motherboard...cant remember which one.
Could it have something to do with the version of directx maybe? I'm on Directx 10.
I'll be searching around, if I find something I'll post it here.