Thanks .... it freed 933.367 Mb for me .... I was looking at 19.07 total available of a physical 20GB drive, of which select all files > properties showed 14.6GB in use (actual), but explorer showed 16.8GB in use ... I'd already purged all the caches, cookies, and temp internet files I could find for both IE and Firefox, so who knows what it found. Glad I looked here, though, that extra gig free is enough to finally defrag. 
