Although we have not tested our controls in VS 2008 Express Edition
after some research I can tell that our WPF controls would have no problem working with VS Express Edition. ORM however is using both a Visual Studio Add-in and a Visual Studio Integration package. As you can see in this
thread Add-ins and Packages are not allowed in VS Express Edition so I believe you won't be able to use ORM. Hope that helps.
the Telerik team