I used to over clock so if I woke up late I'd really end up on time.
But seriously, you can "get" better performance out of your computer. In the old days it could make a huge difference. Now-a-days, it's sort of a hobby just see how far you can push it to get a benchmark. The over-clocks are not really worth the performance tweak. If you can overclock a 6 mhz processor to 8mhz you get a 25% increase in performance, but now we're trying to overclock a 3ghz to 3.4, the difference is very small, and video over-clocks are usually not maintainable for extended play without rendering errors to the screen or harming the hardware and do not provide enough of a performance increase to actually improve game play.
So get yourself a copy of 3dmark and fire extinguisher and post your benchmarks, buddy.