This is a really great presentation, Windows 7 Search and Find features look really useful and I would upgrade my Windows just for this feature as its just what I've been missing.
One suggestion - Please can the Preview pane highlight the search terms too? So when you click on the Preview button the text in the document is highlighted in yellow. I've seen this in other search tools (specifically Enfish) and this feature is really useful.
I can see you are previewing and highlighting in yellow the text underneath the document name in the search - this is useful too so keep this.