There is an environment variable you can set to turn on GPU support for AMD cards. It’s not enabled by default for a few reasons, but if you’ve got a hefty AMD card, it’s definitely worth enabling. I’ve been using it with dual FirePro GPUs for a while, and I’ve only had one Blender file where it couldn’t compile the kernel and use the GPU for both in-window rendering and final rendering. I set the compute device to use both GPUs and all CPU cores, and it screams. Makes a huge difference in day-to-day Blender use for me.
To turn Cycles rendering on for AMD cards:
[FONT=Courier New]setenv CYCLES_OPENCL_TEST all
Be aware, though, if you have an AMD or consumer grade GPU, it may simply not be capable of rendering most Cycles scenes. I have no idea how the HD7750 will handle it, but it can’t hurt to try it out.