Too add to pbcopter's good advice, if the file types you are looking for are of one 'kind'. you can use one of the filters. For instance, pbcopter's examples are all considered documents, so if you compose your search as "kind:doc" (minus quotes), it will find all of the formats that comply with the 'kind:doc' filter.
You can also combine filters. In example, if you were looking for a series of documents in different formats, all pertaining to the same topic and having similar filenames, your search would look like this:
name:*sevenforums kind:docs Your returned results might be: commandline posts sevenforums.pdf using taskmanager sevenforums.doc, etc. If you were to add the tag: filter to the mix, you could narrow your search further (assuming you use tags). Learning the Win 7 search configuration and syntax makes for a powerful search utility. Of course, you may not need more than searching on multiple formats. It's just about what works for you. If you decide you want to look into the capabilities of Win 7 search, here are a few links: Windows Search - Configure and Use Windows Search Advanced Query Syntax
James