Among many other excellent things, there is one that allows BGI to be played with the BGII interface, including all the AD&D 2nd ed. rules not implemented in the first one (e.g. dual-wield for Rangers, and class kits.) There is also one that allows several items that occupy the same slot but do different things to be combined into a single item, so you are not faced with a choice between which ability you value most, or forced to juggle inventory. As an alternative to the BGII mod for BGI, there is another one that merges BG, TotSC, SoA and ToB into a single seamless playthrough so you do not have to import characters from the first game to the second.

I HIGHLY recommend using the multi-player mode to create your entire party for a single player game; you can also use it to duplicate unique items, but even if you just create a party of PCs far superior to NPCs it is worth it, and you can then copy the MPSave folder over the Save folder and go back to playing in single player mode with an entire party of your own making.