Barrie North has written a comprehensive book for Joomla 1.5 to help you get up to speed quickly and to build that killer site you want. This link goes to the book website, and you can pick up a discount coupon there as well: www.joomlabook.com
I have always enjoyed Barrie's writing style and I think this book is a winner. It comes with a CD and a link to a private website with additional resources.
The book is also offered as part of a boxed "learning kit" with video training tutorials and may be a valuable addition to your library.