>My first question is, how do I make a new window/browser pop-up?

There are few different ways you could do this. On any link you can add a target and have a browser window pop up. But the user will need click on something before that, or take some action. The other thing you could do to create the action, is have the page refresh every 5 minutes, something like Universal Thread does.

>
>My second question is, how do I detect that I have a reminder to show?
>- my boss wants me to run a server-side script or app that will check for due, and over-due, reminders

You would have to detect the time on the machine, and the time on page refresh or button click etc.

>- another possibility is to tie the checking to a submit event or some other(?) Post event (are there various kinds?)
>-is there another reasonable approach?

This is a reasonable approach. I think you would have to do something like how Universal Thread, refreshes the page every 5 minutes and you would have to use that and each page refresh to determine if an event is available and pop up the window if it is.

>My third question is a spin off of the second question. Using my bosses approach of running a server-side script or app, how do I know that a user who needs a reminder is in the system...and how do I make the reminder window pop-up on His/Her machine?
>

You would know upon the page request, you have to store some type of user id in session or in a cookie and send it or request upon each and every page request. That would be the only way, I would think of.

Another approach for something like this, is to go to a full fledge Java Applet, which would give you more flexible then a standard pull technology like a web page.

Morgan