I highly recommend you to use WPF instead, if it is possible for you to use Expression Blend, i highly suggest using Expression Blend for Designing UI(s), Storyboards(animations) and customizing UI(s) then you feel like you are walking in heaven :)
Then i suggest you to use templates or themes for WPF. Like zune theme, and if you are interested in Microsoft Office themes, the good news for you is there is an overflowing of themes like this, just google it!
but is suggest you to design your own controls if you are able to use Blend except for those situations that you see you can not do this really.