ASP, PHP, Perl.. They are all Server-side scripting.
you dont need to know one of these if youur doing simple static web page. The main purpose of these language is to create dynamic pages by connecting to database.
You can use VBscript to write in ASP. So if you're familiar with VB script, you definetly should put a little time into learning it.
I do not know much about .net.. I'll learn it in two mounth..