Question: how can I list all checked out items in vs.net 2010 tfs? where in 
vs.net 2010 can I find this /do this?

Answer: 
The "Pending Changes" toolwindow. Select the View > Other Windows > Pending Changes menu items.

You can also use `tf status` command, see <http://msdn.microsoft.com/en-us/library/9s5ae285.aspx>.
Attrice has a nice UI in which you can see these kind of things. You can see the list of all checked out files by anybody and even act commands on these files. See [Attrice TFS Sidekicks](http://www.attrice.info/cm/tfs/index.htm).