Truth is, you're not going to get a significant performance increase out of overclocking a GeForce 4 mx 420. I have one, there's really not much you can push it to doing.

If you absolutely must, make sure you have adequate cooling, like a heatsink/fan combo, or if you're poor like me a desk fan on an open box can do the trick too. Like I said though, there's not a fantastic increase in performance, the change would be so little.

And if you're serious man...the new Geforce FX's come out in February, we're talking some serious muscle. I heard that within a few generations of video cards they'll be able to render things like Final Fantasy:TSW in real time instead of prerendering them. That should be badass.

Hey, there's also lots of tools on the web that let you overclock your GPU nowadays. Usually has a little slider bar that lets you set the MHz. Just don't push it way too far, because it'll freeze up your card, and might do damage. Although most cards like that have fail-safes to keep them from burning up.