Keep in mind that if your going to let your web page run xp_cmdShell you are going to have to give your web account a lot of access to the SQL Server. This brings some major security problems into the mix. You have the same problem if you start a job.
I'd recommend getting the result set from the SQL Server, and having the ASP page on the web server create a csv file on the web server. I usually use TarsusIO. You used to be able to get it from www.tarsus.com, but it looks like he didn't re-register his domain.
Search google for "tarsusio", and you should be able to find somewhere to download it.