Hey Nalster, welcome to AOA Forums.
You need to access BIOS, from where you can raise the FSB (Front Side Bus) in order to overclock. Your particular board should support 1 MHz increments of FSB. I just found that your motherboard calls this "CPU Frequency" in BIOS.
Try upping just a little bit at the time. Let the computer boot into windows, and run some testing to make sure it is stable. (I recommend Folding@home, but there are lots of others out there). If it is nice and stable, you can go back into the BIOS, and up the FSB another notch or two.
Watch the temperatures as you go, you don't want to toast your CPU.
I think you will find this link handy, btw:
http://www.ocworkbench.com/2003/ecs/...a2gallery1.htm