It's not a good idea to simply turn everything off: 'Off' doesn't mean best.
These are the settings I have (a gaming rig) for BGmain.exe:

Ambient Occlusion: Not supported for Baldur's Gate
Anisotropic Filtering: 8x
FXAA: Off
AA Gamma Correction: On
AA Mode: Override application
AA Setting: 4x
AA Transparency: 8x Supersample
CUDA GPUs: All
Maximum Pre-rendered Frames: Use 3D application settings
Multi Display/Mixed GPU: Single display performance mode
Power management: Adaptive
SLI rendering: NVIDIA recommended
Texture Filtering - Anisotropic optimisation: Off
Texture Filtering - Negative LOD bias: Clamp
Texture Filtering - Quality: Quality
Texture Filtering - Trilinear optimisation: Off
Threaded Optimisation: Auto
Triple Buffering: Off
Vertical Sync: Use 3D application settings

Thanks again. I always assumed AA didn't work that well any of the IE games.

I've never had an issue with AA in any IE engine game, however it's possible that some graphics cards/drivers can cause artifacts (shimmering, lines etc.) with AA turned on. If that happens, just switch AA to 'Application Controlled'.

Yes, DDrawFix is a third-party mod (fix). It does get installed automatically with the latest GOG version, but TuTu does not install it. Install it, and don't forget to set your optimum options in BGConfig.exe, something many people forget to do, or simply don't know it exists.