OK, right, Unix. Forgot from before. You can use notepad for everything. Remember that editors like Visual Interdev or Visual Studio .NET handle specific functionality that makes coding easier (like intellisense for one), but that doesn't mean you can't use another editor, like notepad. It just involves more work.
The ASP page can be edited, you won't have the coloring and intellisense from Interdev, but it will work. Post it to the web server, then open it in the browser by going to http://localhost/<folder>/<file>.asp, and it will bring up the file.
Even .NET, the framework comes with a vbc and csc compilers to compile VB
.NET or C# code. You don't need to buy VS.NET, but you can if you want because it has a lot of features that it handles for you (such as compiling, adding references, intellisense).
Editor's are nice, but you don't have to. You don't have to compile ASP like you do with VB
.NET, because there isn't any code-behind pages that are compiled to a component.
All scripts in ASP are included in <% %>.