It depends on your training and profficiancy obviously. The more you practice nailing the localizer and glidescope down to minimums the lower you'll be able to go as far as personal minimums. I've seen many students that just go "wild" at about 400 feet, and if you have trouble tracking the localizer right before minimums, obviously you should have higher personal minimums. I can't stress enough how important it is to practice untill you can nail that localizer.
I know from personal experience that if you are half a dot off on the localizer at minimums if a 727 or 737, you are simply NOT going to be landing on a runway, you better go around. As important as it is to be on the localizer and glidescope in a GA plane, it's that much more critical in a transport catagory aircraft, and you better get used to the idea of nailing the ILS or any other associated instrument landing approach.
Given my fairly extensive IFR sim training, in level 6 FTDs, up to Level D simulators (737), I feel comfortable going down to minimums as far as my piloting skill, however there's more to it than just basic stick and rudder, because at least half or more of it is ADM. If Wx is right at minimums, you are toying with fuel and the situation. Are you going to try again if you go missed? How is that alternate looking? How has weather changed at and on the route to the alternate since you last looked at it? Very quickly one can see that when the Wx is at minimums it may be better to just go somewhere else.
I have done approaches in real Wx, not just simulated (although the hardest approaches I've done were in the 737 and 727 where they "throw everything" at you) and it is pretty exciting, but with enough training and practice it can be done pretty safe if the conditions are fairly safe (like stable, fog, etc). I think the biggest factor to my own personal minimums is the amount of practice with instructors down to minimums, and the wide variety of conditions and approaches in radically different aircraft that I have been exposed to.
Some factors that determine my minimums at any given time are;
-Number of pilots on board
-Aircraft capability in ice (because often where I'm at it may be clear above, but cold and a layer of clouds hangs out at approach-altitudes just waiting for something to come by so the moisture can freeze to it)