The installer, obviously
No DRM so no CD crack needed
Some of the games have a few INI tweaks already applied (like increasing the number of AI navigation nodes in Torment)
Everything else is identical, right down to the transparency issues on certain video cards which is especially problematic with Planescape: Torment.
On the plus side, this meant that all of those awesome IE mods worked right off the bat.
edit: Oh, those Win 7 glitches that I mentioned also happen in XP 32. It's more a video card driver thing than operating system.
