i do a backup of my stuff manually each month via an ext. HD. right now, i was backing up my AppData folder (so much is in there!). being anal, i compared the size of my laptop's internal HD compared to the ext drive when it was done. results: internal: 5+ BG ext. 2+ GB so i compared the size of each subfolder to see if they match up and, yeah. conclusion: windows is hiding something from me. but what? p.s. yes, i have "show hidden files and folders" ticked.