Cannot Delete Files In Temp Folder

I've been handed down a computer. It's a Sony VAIO, and comes with two hard drives. Windows is installed on an 80GB hard drive, which had (when I first booted the computer) only about 0.5GB free.I eventually found out that the temp folder under "C:Documents and SettingsMY NAMELocal Settings" was taking up almost 60GB.I emptied it of all but two files, both ending in .tmp (i forget what they were called). They were both 144KB in size. I couldn't delete them as they were "in use".So why does the computer still think that the temp folder is so enormous? Right now it says 57.5 GB. What should I do about it? I have checked that hidden files are shown, and run Cleaner and Disk Cleanup.