For the Enhanced Edition released in 2013, see Baldur's Gate II: Enhanced Edition.
Patches are available to fix various issues.
The 'Tutu' mod known as BG1Tutu allows the importing of Baldur's Gate files into the Baldur's Gate II engine. For the Dungeons & Dragons Anthology: The Master Collection version copy BGate2.mpi from the CD into the installation folder prior to installing Tutu.
The BG2 Fixpack is a WeiDU compilation of fixes for Baldur's Gate II. Several modders began working on a new WeiDU fixpack to address the numerous bugs that have been identified. Fixpack currently includes all of the fixes addressed by Baldurdash (including the Game Text Update) and several hundred new bugfixes. The project is ongoing.
The 'Trilogy' mod known as BGT is an alternative to Tutu that also allows the importing of Baldur's Gate files into the Baldur's Gate II engine. In addition, BGT uses a dynamic system to transfer players from the end of Baldur's Gate to the beginning of Baldur's Gate II. For the Dungeons & Dragons Anthology: The Master Collection digital version, simply rename the Baldur's Gate folder to Baldurs Gate without the apostrophe to make it command-line syntax friendly. NOTE: Must have both Baldur's Gate and Baldur's Gate II installed and their correlating expansions (Tales of the Sword Coast and Baldur's Gate II: Throne of Bhaal).
It's worth noting there are cost effective re-releases and for ~ $15 I suggest don't be miserly and do that. I played Icewind Dale on a modern iMac: the screen resolution was better, the text more readable, and using a "magic mouse" to help navigation is quite nice. Quite pleasant compared to the "old un-maintained pc version".