Dukeres is a easy to use windows texture extractor and importer. Download
Duke textures come in set sizes, those sizes are,
"4, 8, 16, 32, 64, 128, 256, 512, 1024"
All sizes are in pixels.
You can download textures from any of the following sites.
::: Wad Farther
::: Quake2 retexture project
::: Texture sets
::: PI Design