searching multiple items

I was wondering if anyone knew if it were possible to search for more than one things such as extensions or keyword?
All I can find in Vista is the ability to refine your search further with the advanced filters, but I can't find a way to view a selection of documents like in the screenshots of the earlier Vista builds, i.e. An All Documents Virtual Folder. (http://msdn.microsoft.com/windowsvista/prodinfo/what/discoverable/default.aspx)
Examples: *.docx & *.ppt files or perhaps documents that include content on biology & biochemisty.
Is it possible to do such a thing or has microsoft overlooked such a simple thing?
Thanks