如何“推送”（ASP.NET）网页表/网格中的单个单元格的更新？

I'm building something similar to a price comparison site. This will be developed in ASP.NET/WebForms/C#/.NET 3.5. The site will be used by the public, so I have no control over the client side - and the application isn't so central to their lives that they'll go out of their way to make it work.I'm building something similar to a price compa