Here is a little tip on the usage of the active checkbox in the nsurvey settings. Most of you might be wonder what this checkbox is for.
In fact there is a "hidden" feature of Survey that let you set the SurveyID on the web control to -1. Once you've setup the SurveyID property to -1 the webcontrol will automatically take and use the activated survey in the database, there can be only one activated survey at one time.
This way you can change a survey at any time without having to change the survey id from the page on which you've pasted the web control code.
Note : this checkbox should have been named "Default survey".