I think newer ATI cards are (I think...lol). I think Nvidia cards are less likely to work. More info here. Also a link there to even more detailed info. If you have a graphics chip on your board, it's likely not openCL compatible.

If you're not even sure what's in your computer, Piriform makes a small program called Speccy that will tell you all the hardware that's in your computer.

Laurie