Is there a sequence to update NIS 2010 and firefox 3.5?

hi i was wondering how i should update my firefox to 3.5 and my nis to 2010 some people say it is glitched and firefox wont open wen updated is this true? and also what order do i update in?(firefox first then nis?)

 

and also if i buy norton 2010 on cd can i add the subsciption on to the current one i have?

Message Edited by naidoo on 09-28-2009 08:38 PM
<<Edit: Subject edited to reflect the issue>>
Message Edited by JerryM on 09-29-2009 09:15 AM