Discussions

I am curious as to what the general opinion is on how much noise is expected from your neighbours.  
 
We are dealing with some noise issues at least one night each weekend from our next door neighbours. What happens is they always have friends over to drink until drunk and then they get stupidly loud. We have tried to remain patient and usually when they are out there we have the windows shut and turn some fans on and you can just hear the occasional thing. It is still frustrating though because we are regularly enough woken up each weekend at 2 a.m. or thereabouts from them getting loud, yelling, etc. We have small children so it is doubley frustrating.  
 
For me, I have been taught to respect those around me and tend to go a bit overboard the other way. I don't even like using our rototiller in the middle of the day because it is so loud and I worry it will bother someone. And because I am so sensitive to it, I know sometimes I have unrealistic expectations. But, that being said I also really question this complete lack of respect for those around them, coming people in their late 20's (one of whom is a teacher). Is this what is normal and considered OK nowadays?  
 
Hence the reason for this topic, how much do you think is too much noise? What is your personal limit on noise from your neighbours? And what do you yourself consider OK to be putting out for noise to your neighbours?