Validate Checkbox and Checkboxlist
If we want to Validate the Textbox, Dropdownlist we used Validation Server Controls available in ASP.NET
Suppose if we want to validate Checboxlist or checkbox , some member validate through Javascript its good , some feed if its similar to Validator controls it should be easy to validate,.
so here is the link its similar to validation Server controls just Download the skmValidator Controls and add it on toolbox just drag and drop and set the errormessage , validationgroup, controltovalidate etc..
http://aspnet.4guysfromrolla.com/articles/092006-1.aspx
If you want to do on Client side check this link
http://www.dotnetcurry.com/ShowArticle.aspx?ID=197&AspxAutoDetectCookieSupport=1