Some versions of Thief, such as Thief Platinum, may come already patches, or have the patch file on your game disc.
Patch installer for Thief 1 / Thief Gold:TFix_1.27 - (Note - TFix is currently using NewDark v1.26) 159.6 Meg.
Adds EAX (Creative Labs' "Environmental Audio Extensions") support, joystick support, cheats, and several bug fixes.
Thief Enhancement Pack 2.0 alpha - 779 Meg.
Thief gold HD texture mod - 1228 Meg.
Thief dark project Sound FX Enhancement - 133 Meg.