There is a way to do it with IIS. You need to configure the application to run under the IWAM rather than IUSR account but telling it to run as a separate process. If it crashes it will not take down the rest of the server.

You can use the MetaBase editor (downloadable from Microsoft's web site... do a search for "MetaEdit" in the knowledge base) to configure the number of times it will be restarted in the AppOopRecoverLimit key when it crashes (default is 5... set it to something much higher if you'd like).

That said, take a closer look at your scripts. I find scripts which use GD or which use DBI with a large LongRealLen value are more crash prone. Also, scripts which use DBI and do not properly finish statement handles are also crash prone, especially if the SQL query sorts large amounts of data.