Are you aware that:
(1) Your question has *NOTHING AT ALL* to do with ASP. ASP runs on the server. You are wanting code that runs on the client, in the browser.
(2) If you save the data on the local system, it will only be available on that system. That is, no other users will be able to see it.
(3) So long as you write using VBScript code in the browser, only people using Microsoft Internet Explorer can use the code.
(4) In order for the browser (even MSIE) to write data to the local drive, the HTML page *MUST* come from a "Trusted Server". In most cases, this means it will have to come from some inTRAnet server, not across the inTERnet.
(5) Even coming from a trusted server, the user will have to allow the page to use code that is considered "unsafe for scripting". That is, the user will have to say "OK" or "Yes" when prompted to allow the page to do the unsafe code.
If you are aware of all of the above and still want to proceed, then yes, it can be done.
CSV willl be easier to create. VBScript doesn't have any built in controls to make it easy to create XML data.
An optimist sees the glass as half full.
A pessimist sees the glass as half empty.
A realist drinks it no matter how much there is.