This may also be of some help. If the resource you're downloading is an arpack ( ArtRage package ) file or any ArtRage resource, it can be used on both Windows or OS X as Artrage resources are not platform specific. See my guide here for more information on download various ArtRage resources:

http://forums.artrage.com/showthread...Rage-Resources

If it's a third party Photoshop plugin or utility, then it will likely be OS Specific, unless the people that wrote the utility or Photoshop plugin provide a version for both operating systems.