Per the recommendations on the forums, I installed BGTutu and Gibberlings widescreen mod. Tutu installed fine, but Gibberlings always tells me to run the installer "in my Infinity Engine game directory". I've run it from my BG1, BGTutu, and BG2 folders, all with the same error message. Any help anyone can give me? Failing that, can anyone recommend a way to run BG Tutu and BG2 at 1600x900? Thanks, everyone.

After you have downloaded the Widescreen mod setup file and run it, do NOT install it to the default installation folder, which is:
C:\Program Files (x86)\Black Isle\BGII - SoA

Do NOT. You must point the installation to your TuTu game folder, after which there must be a folder named 'widescreen' and a file name 'setup-widescreen.exe' in it. I don't quite recall if the installer calls the setup file, but if it does not, you need to run 'setup-widescreen.exe' inside your TuTu folder.