As to what program you use it depends on the type of card you have. I prefer Riva Tuner for my Geforce 2 PRO. It helps to have good airflow in your case, a gpu heatsink/fan, ramsinks, and maybe even an extra fan blowing onto you card. While overclocking, take it up in small steps and then test for a while with 3Dmark 2001. If you see any twinklink pixles or other artifacts than take it back down a few mhz and test it for stability. You will probably get the most performance from overclocking you video card's RAM but overclocking the GPU can help some. Hope this helps.