This may not be the answer you're looking for, but I would actually recommend against using the BiG World mod...
I decided to start a new BG game myself after purchasing the series here a few months ago and did rather extensive research on most of the available mods, scrutinizing the differences between BiG World and BG1Tutu in particular, and I found out that BiG World just felt too bloated and that they seemed to have taken too many liberties with the original content, making it much more prone to glitches and other issues than BG1Tutu. So, for the most "authentic" Baldur's Gate experience, while still benefiting from all the improvements of the BG2 engine and full widescreen support, I ended up using the following mods:
G3 Widescreen Mod BG1Tutu LadeJarl's Original BG1 UI for BG1Tutu BG1 Unfinished Business One Pixel Productions Ghostdog's PS:T UI Mod (I only used the fonts from this mod, to increase the dialog font size in the game)
G3 Level 1 NPC's*
This selection of mods provides, in my opinion, an amazing "modern" BG1 experience while still retaining all of the original's nostalgic elements. And, even more important, it's a stable experience -- I have not experienced any glitches or bugs, and I plan to use this same collection (excluding BG1Tutu and BG1 UI of course, and using Pocket Plane's BG2 Unfinished Business) for BG2.
I am posting this from work by the way, so I might have forgotten something, but I'll double check when I get home.
* This last one was just to change a few of the NPC's starting proficiencies (which are changed in BG1Tutu to accommodate the BG2 engine) to make more sense, like giving Khalid the Long Swords instead of Bastard Swords proficiency and Jaheira Quarterstaves instead of Clubs.
