Your opinion

My 2 cents:

Depending on how fast you want it, you can wrap each panel inside an UpdatePanel, or just to test the whole thing, add only one updatepanel around the 4 panels, will be slow but at least you'll get the idea. I would say the best practise will be one UpdatePanel around each panel.

You can use UpdatePanel for this

http://www.asp.net/ajax/documentation/live/overview/UpdatePanelOverview.aspx

Also seehttp://www.asp.net/ajax/documentation/live/tutorials/ExclusiveAsyncPostback.aspx