A free tool, FileSeek could provide fast and focused searches in the hands of someone comfortable with techie techniques such as regular expressions and wildcards, but non-techies might be more comfortable with the built-in Windows search.
FileSeek allows for specific searches that might include certain file types or names and exclude others, and can use wildcards in those specifications. For example, typing in "*.txt" in the Include field will tell FileSeek to only search files that end with .txt.
In its search results, FileSeek reports the filename, full path, and whether the result is based on finding a match based on the file's name or on information within the file.
If FileSeek found data within a file, it will report the line number where it found a match, and the selection of text that matched. If you click a particular result you'll see a preview of the matched text in the bottom of the program window; double-clicking will open that file.
FileSeek can perform detailed, specific searches if you're a technical user, but it could use a few more user-friendly features. For instance, there isn't currently a quick option to search everywhere if you have multiple hard drives. You'd instead have to search each drive in turn. But the program's maker is releasing frequent updates which FileSeek will check for automatically, so it may soon become more polished.