I have Windows PX 32 bit and ATI RD 4800 and I need to install OpenCL. I wanted to install ATID SDK APP to get OpenCL but I found, there is not XP version on the site here:
http://developer.amd.com/tools-and-sdks/opencl-zone/amd-accelerated-parallel-processing-app-sdk/
APP SDK officially doesn't support Windows XP. Please use Windows 7 or later version.