Spouse's 5 year old Dell laptop kept running out of disk space. Me, a non-Windows user, didn't hold out much help for fixing it. But turns out 2 mins after installing "WinDirStat" (which, apparently, is legit and not chock-full-o-spyware) I realized the problem was the buggy and unused "Dell Support Assist" software filling half her hard disk with snapshots. Uninstalled it, and problem fixed. Amazing.