Create a design for a dynamic appointment system. 

How would you design an ASP.Net system with the requirements listed below in .Net 1.1?, in .Net 2.0?  Which would you recommend?

Requirements

Administrator user:
1.  Clicks on link or image to indicate they want to create/add a new appointment
2. Fields show up to gather input (either a popup screen or dynamic) without reposting the page or taking the user to another page.
3. When finished, press clik to add to the appointment store or cancel to go back to where I started
4. Do no take the user to any other pages

Normal User:
1. Click on link that will download a vCalendar or iCalendar file of the appointment (must be generated from the appointment store)
2. Click on link or image to see information about the appointment
3. Do not take the user to any other pages

Desired Flexibility
1. Be able to switch the appointment store with little effort (exchange, sql server, xml, etc.)
2. Wrap all logic into an asp.net server control so it is reusable on other systems