My best advice for OpenCL development is to use a Mac platform:
Mac OS X 10.6 laptop (even entry-level w/ GeForce 9400M) for development, because OpenCL is fully supported natively on both GPU and CPU, enabling to optimize code for both.
Then run the code and tune it on a Linux server W/O X11, to avoid speed limits and watchdog problems :-)
I would stay with one hardware vendor, for me, and I know just one that have a full range of OpenCL-enabled GPU, enabling development on low-end laptops with IGP, and offering up to server-grade racks for production sites. The other vendor still have big performance hits on it’s old range of GPU, and new GPU (that are promising) are only available for desktops and hard to find in retail actually.
The first have disclosed it’s next generation, that will stay compatible but offers an architecture that is totally oriented toward gpu-computing, offering a clear upgrade path for 2010, and enabling easier port of CPU algorithm as-is.
It’s not a matter of name, because these 2 companies do impressing products, I owned products of both, and was really satisfied, but in term of actual implementation, GPU range, availability of laptop OpenCL solutions, OS implementation of OpenCL, support, nVidia is far ahead, at least one generation ahead!