Alright, so what I think you're saying is that the Northbridge has a set operating speed (in your example 1GHz), and that speed never changes regardless of what you do to the FSB. So, the operating speed is already maxed out, but the ratios that multiply to that operating speed are variable (200x5=1000, or 333x3=1000. You can't make the Northbridge run faster, but you can tell it to run at tighter timings (thereby requiring a higher multiplier) by using the jumper settings. Is that correct?
So, in your opinion, for my 425MHz FSB it's best to have it at the 266 jumper setting for tighter mobo timings, rather than the 333 setting? By the same priniciples, shouldn't I be using the 200 setting instead for even tighter timings (assuming I can reach 425 FSB at that setting, I don't know)?