Finding user SID
Occasionally you may want to know the SID of a windows user. If that made no sense to you, read no futher, this snippet is not for you.
Open up REGEDIT and browse to this key:
Here you will find a list of SID’s, under each is a subkey containing the name of the user it is associated with. Run through them until you find the username you’re looking for and bingo, it’s parent key is that users SID.
Found via petri.co.il