Tweakers Australia has just posted quite a lengthy article on Video Card Overclocking & Cooling. It covers many things including all the theory, how to overclock your video card, what settings to adjust in the BIOS, what driver settings to adjust, and how updating your video card drivers can improve performance. Here's a snip:

    "So we have a core based on a .18 micron fabrication process running at 200MHz. What is its potential? Not much. Because the core is based on such a "large" fabrication process and because it is already running so fast - we won't be able to get much out of it - in theory that is. As an estimate, I think I could get about 10% out of it. 10% of 200 is 20. Thus, we should be able to get the core to around 220MHz. Now, let's look at the RAM. The RAM is 5.0ns EliteMT DDR-SDRAM. The ns rating refers to the timing of the RAM in nano-seconds. To get the speed at which a certain ns rated card can run it, merely divide 1000 by its ns rating. Seeing it's DDR-SDRAM, we double this number to get it's effective DDR speed, so that's 400MHz, which is what the card is running at. That's its theoretical speed though. Now let's consider a 10% overclock of the RAM, that's 220MHz, now DDR it- 440MHz. That's not a bad increase! How about some numbers, to use these formulae you need to know some technical information about your card. If you don't have any idea, just ignore the formulae and continue on to Video Card Overclocking."