Stuff: Agreed . .
Also I believe the default icon res is 96 dpi, would need to research to confirm.
Dots per inch doesn't matter, I'm quite sure the Windows icon format doesn't even contain any definition for that concept. The icons that GOG bundles with the games contain 256x256, 48x48, 32x32, and 16x16 sizes, at least the former three in 32-bit colour, and the latter two or three in 16, 8, and/or 4-bit colour.
While Windows icons can theoretically be any size, the by far most common are the ones mentioned above. 96x96 is sometimes used but only in special cases (Windows XP "very large" folder icons that show the contents of said folder, for example), for most cases a 256x256 icon is used and scaled down on demand, 24x24 is also relatively common but is mostly used for toolbar buttons (and, I think, for notification icons), in actual folder displays, the 32x32 icon is scaled down instead (even if a 24x24 icon is available).