You can use the following code to get valid user for a specific team project:
List<string> displayNames = new List<string>();
TfsTeamProjectCollection tfs = new TfsTeamProjectCollection(new Uri("http://tfsservername:8080/tfs/collectionname"));
tfs.EnsureAuthenticated();
WorkItemStore workItemStore = (WorkItemStore)tfs.GetService(typeof(WorkItemStore));
WorkItemTypeCollection workItemTypes = workItemStore.Projects["Agile"].WorkItemTypes;
WorkItemType wiType = workItemTypes["task"];
var allowedValues = wiType.FieldDefinitions[CoreField.AssignedTo].AllowedValues;
foreach (String value in allowedValues)
{
displayNames.Add(value);
}
However, for your data-binding requirement, could you please offer more information? By the way, what kind of project you're working with? A winform project?