BG1&2 using the BGT mod.
http://www.gog.com/en/forum/baldur_s_gate/baldurs_gate_2_essential_mods/page1


1. Fully install Baldur's Gate: The Original Saga

2. Fully install Baldur's Gate II Complete. If you're installing from CD, make sure you update it to version 26498.

3. Download Baldur's Gate II Fixpack (http://www.gibberlings3.net/bg2fixpack/) and extract it to your Baldur's Gate II directory.

4. Run the newly extracted setup-bg2fixpack.exe (if not automatically started). Only core install.

5. It is safe to select yes for all the optional fixes, but if you want to learn about each in detail, consult the readme file that comes with the fixpack.

6. Download BGT-WeiDU (http://www.shsforums.net/index.php?app=downloads&showfile=54) and extract it in your Baldur's Gate II directory.

7. Run the newly extracted Setup-BGT.exe and follow the instructions. You may need to run it in administrative mode in Windows Vista/7.

8. Enter Baldur's Gate I's directory when asked (if not already provided)

9. Wait for BGT-WeiDU to finish installing.

10. Go to your Baldur's Gate II directory, then find and run the file Setup-BGTMusic.exe and select 'Hybrid Baldur’s Gate/Shadows of Amn/Throne of Bhaal music'. This makes it possible to hear the original Baldur's Gate music when playing Baldur's Gate I.