Gimp download page
GIMP should run on any NT-based version of Windows (NT4, 2000, XP or Vista). Older GIMP versions (2.0.x) could also work with older versions of Windows such as Windows 95 but they are not supported anymore. The amount of memory can be an important factor, especially if you intend to work on large images. A minimum of 128 MB of RAM is recommended, but the more RAM the better.