Dynamically and in real time update web page contents

I need to create a screen that is automatically updated every minute or so with fresh data from a server-based data source, perhaps a simple text file or XML - and is displayed as a web page.

The screen will show a list of items that can be marked with a red, yellow or green icon, as to indicate their status. Each item has a drop-down where you can select/change the current status. So, when a user changes the status for one of the items, every screen monitoring this web page will be automatically updated.

I'm a pretty novice web programmer (I only have experience with desktop programming, VB and a little C#), so I'm really just hoping for a quick push in the right direction here. I assume that this really isn't all that difficult to implement. Am I wrong? And where can I find more info on how to do this? :-)

I really appreciate any help I can get. Thanks in advance!