Overclocking
As it's been asked for, OVERCLOCKING GUIDE GO!
CPU
Tools
Essentials
Clockgen - A windows based overclocking tool
Handy Extras
Orthos - A Stress test app based on Prime95
Guide
Basically, what you wanna do is up the FSB a few clicks in Clockgen (3-5 at a time for a start), wait, Repeat.
Take notes of your speeds (on paper) every time you change them.
Once your machine crashes, reboot and go to the last stable speed. (the one before it crashed)
Leave it at that speed for a while
If it's stable, run orthos on the default mode (Blend - stress CPU and RAM) and wait.
If orthos fails quickly, downclock a little and try again. I like orthos to run for at least an hour without errors - longer is always better (tnwss)
More info
Beyond that, you'll wanna up voltages in the bios (vcore) carefully as that helps stability a little, allowing you to get higher FSBs
GPU
Tools
Essentials
ATITool - Automatic Graphics card overclocking app - Supports ATI and Nvidia cards
Handy Extras
3DMark - Graphics benchmarking app, Very good for stress-testing cards (Use the newest version your card will run)