Hello Fabricio Frontarolli,
You can style the controls. You can get one of our existing themes for Silverlight (for example Office_Blue) and modify some of the brushes in the resource dictionaries. For some of the controls you may need to edit their ControlTemplates. At the same time if a new version of the control is released you will have to migrate your custom theme to the new theme. This does not happen often but is possible.
In general styling the controls will require a lot of work. We have 2 themes scheduled - Transparent (a glassy one) and ExpressionDark. Eventually we will consider Office 2010 after that and MS Toolkit theme that will much the MS controls (the one you need) I am not able to promise it though and I don't have schedule for it.
All the best,
the Telerik team
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