Korell, or you can try to use the 1.10 version of TFix I linked to. It uses DDFIX, and as far as I've found works just fine on my NVIDIA card, and Alienware machine (stable even). It keeps the Thief 1 engine as the thief 1 engine, so no 'weird' anomalies as far I've found.
At least until people 'fix' as much of the stuff as possible, and come up with an improved 1.19 patch for the game.
But Thief Gold by itself doesn't really need the features of the Thief 2 engine or the new 1.19, unless you intend to use some of the fan addons like say things that replace assets with improved graphics (some of the fan stuff pushes the original vanilla engine to the limits of its poly counts) or add bloom and other special effects. Future fan levels will undoubtly require 1.19 at some point, as they will be exceeding the limits of the older versions of the engine. I could never get 'bloom' patch (not something I use most of the time, but just goofing off with) to work on Thief Gold, but for whatever reasoned worked on Thief 2 with no troubles.
Seriously the main reason DDFIX was designed originally was to fix fog, improved shadows, and transparencies in the skies of Thief 2, and those features aren't even an issue in Thief 1, since it was a more primitive engine (no weather, basic skyboxes, etc). So there was very little, that DDFix had to fix graphically in Thief Gold.
Personaly I've found I technically don't have to have DDFIX (or any new engine patches) to play ThiefTDP/Thief Gold, it was some of the stuff later added to DDFIX that was useful for Thief Gold to fix other issues (video playback fix, and setting cpu to single thread mode). Plus if you like it, and I do, use of native monitor resolutions.
Post edited December 23, 2012 by Baggins