Get the mods here for BG1 tweaks, BG2 fixpack, and BG2 tweaks. Best of all, this version will play not just on PC and Mac but also iOS and Android. With an upgraded Infinity engine, the “Enhanced Edition” can be pre-ordered for $19.99 and has a November 30, 2012, release date Baldur's Gate II will follow later. “ Baldur's Gate Enhanced Edition” is in progress thanks to Beamdog, which includes many ex-BioWare employees who worked on the original games.
I should mention that there is also a commercial revision of the Baldur's Gate series underway. While they're not linked from BioWare's modern EA-era website, you can still find them on the download servers here, here, and here.) (If you're dusting off your old install CDs, you should apply the official patches first. There’s also a separate widescreen mod that works for all the Infinity-based games. The BG2 fixpack, for example, consists of core fixes (the only thing you absolutely need), plus a bunch of “optional but cool” extras that the accompanying notes explain.
Each mod archive contains a number of separate installable mods, but in each case one text-based installer takes care of all of them for you.