for my old pc, actually was my main before christmas, I used the nvidia overclock utility (can't remember the actual name). It has an auto tune function which autmoatically changes the clock reference to how high it can go while still being stable. specs were nforce 6 chipset amd athlon 3500+ (2.2gz single core) and 2gb of 667mhz ddr2.
Well, if you set it 1:1 since your FSB is 1066 (4x266) you ram would start off at 533 (2x266). That should give you a bit of overclocking headroom and allow you to raise your FSB to 1333 (4x333) thus giving you a RAM speed of 666 (2x333). Since you have a multiplier of 7 you would end up with a speed of about 2.33GHz. Raising your FSB farther means clcoking your RAM past it's 667 spec so you would have to raise the RAM voltage and loosen the timings.
Well, with DDR2 800 you could raise your FSB to 1600 (400x4) before maxing out your RAM speed, assuming a 1:1 ratio. Of course that's if your motherboard can take it anyway . Only one way to find out. Good luck with it and hope you get a good OC out of it.