You can overclock it using aticonfig and easily gpu mine with m0mchil, diablominer, or others. You will probably need to use the "-f" option on many of these with a high-ish value to prevent slowing down graphics for your own use. For example, if you are running X and moving things around this will be slower but the -f option on many of these will enable you to tell the gpu miner to step aside and give more priority to your applications. See http://forum.bitcoin.org/?topic=1721.0;all
for some samples
You will need to install pyopencl and the ati catalyst drivers as well.