Andrew Flick announced that Infragistics WPF Express Edition will be free as well. Before this release, xamDataGrid suffered a lot of performance problem. It seems that they have fixed various performance problem. So I think I will give it a try again later. To try it out visit http://blogs.infragistics.com/blogs/andrew_flick/archive/2007/09/13/infragistics-netadvantage-for-wpf-express-aka-free-grid.aspx for more information.