I've installed Baldurs gate 2 on Windows 7- 64 bits and its running properly. The only problem is that I'm unable to edit the Baldurs.ini file to allow access to the in-game cheat console.
In the case that you have installed the game in the default directory (Program files (x86)) then you will not be able to access the cheat console (CTRL+ SPACEBAR) during the game. The only solution is to install the game in another directory.
First if you don't want to lose your save game, you can backup them manually.
C: >Users>Username>AppData>Local>VirtualStore>Program Files (x86)>BlackIsle>Baldurs Gate > Save
Copy the contents of the Save folder to another location and unistall BG2 and reinstall it, e.g on another partition.
Once done,launch the game and create a new character and Save the game.
This will automatically create the "Save" folder, in the Baldurs Gate 2 installation directory.
Close the game an transfer your save games back.
Note that:You will now be able to edit the .ini file and access the cheat console.