I do Sandra Sisoftware testing. Burn in, mem benches, CPU benches. I just build a system for my parents and will be doing memtest86 and prime95 in a while. They are good tests as well.
Up the FSB as MUCH as you can, and up the CPU multiplier as MUCH as you can. Watch the temps, and up the Voltages of your mem, CPU and chipset no more than, 2.8V, 1.8V, don't know how much you can pump voltages in the chipsets.
when you overclocked too much you'll know cause it'll:
1. not boot Win
2. random reboots
3. no post
4. beeps beeps beeps
5. no screen in which case you need to clear CMOS.
The XP1700(1.43) is currently at 195x11 @ 2.25Ghz so an 820Mhz overclock ain't too shabby....LOL