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.