Thanks.
I am happy about this list and Drupal.
That's great ;)
Regarding the removal of the two lines I mention you, your Drupal installation would behave in a perfect normal way. BUT (and there's always a little but ) if you would have a very (I mean very) busy website regarding the creation of nodes/users etc... You may encounter some problems (but I don't think it will happens).
To make you understand the meaning of this LOCK, is to prevent that 2 people simultany make 2 select from the sequence table (the one who give users/nodes their ids) before the update occurs and increment id. So those people would create a user/node with the same id and this is a Database problem. This kind of races shouldn't occur if you have a normal traffic website (IMHO).
Regards
Tostinni