google clockgen...theres a little explaination on it...but returns on that system would do you little to no good...it doesnt even have a agp slot on the machine
If all else fails, your could try other programs like SetFSB and CPUCool: http://www.cpufsb.de/index.html http://www13.plala.or.jp/setfsb/
You'll have to google if your PLL is overclockable, although if your PLL isn't included in Clockgen (which is discontinued) then it might be in one of these other programs.