I was just wondering if there were some really important reason to have the game installer divided in three files. Did the DVD version of the game work in a similar way?
It feels weird having those bin files floating around, without the GOG icons.

2gb is the max file size for Gog. I don't know why, but any game over 2gb is split up like that.

My understanding is that WinXP has some issues with individual files larger than 2 GB (don't quite understand the specifics, someone feel welcome to elaborate), so limiting the installation files to 2 GB is probably to make sure that no issues occur with WinXP installations.

The only windows-related size limit that I am aware of is the FAT file system's max file size (4 GB). This applies to any FAT32 partition though, regardless of operating system version.

From what I read it sounds like it's some kind of caching issue. But like I said, I don't quite understand the specifics beyond that.

Thanks for the answers! I guess the most probable reason is the caching issue, or the maximum memory per process XP can manage. I am tempted to run some absurd tests in a XP machine.

The maximum filesize of a FAT32 partition is 2GB.
Given that all versions of Windows can use FAT32 and USB media currently tends to have that limiting the filesize to 2GB ensures that the files can definitely be stored/used anywhere.

Actually I think it has more to do with the file size and downloading through a browser. If you see using the GOG Downloader gets you the whole thing at once.

no, it's not. splitted 2gb files as well. just downloaded advent rising using the gog-downloader.

Yes it downloads the separate files to keep the installer the same but it did all at once. With the browser you would need to download all the files separately.