JAM Software has a free utility called UltraSearch which is available for download here. UltraSearch is designed to search multiple directories on multiple drives for files and content. It does not create a searchable index, but instead uses the master file table of the Windows file management system.
I tested it out tonight, and I can attest to the fact that it gets much faster results for file type and file content searches than Windows Explorer or other utilities I have used.
RegEx searches can also be run in UltraSearch.