HD Space vanished? Duplicated files maybe?

[Kamikaze]

Hello,
My 24" iMac (10.4.10) had around 20-25gb of free space left on it. I quit converting my DVD collection until I could get a mass storage/backup solution set up this weekend. Last night I had the above free space left out of the 232 available. My kids may have been clicking on things I'm not sure. When I got home today I had a message that my startup disc was full. I now have 2gb of free space left.
Is there any software/utility that i can use to help track down duplicate files or that can tell me what the last files were that were modified? If not I will copy my files that I need to the new storage and wipe the drive and reinstall everything then move my docs and media back to it.
Thanks for any and all help with this.
One more thing my unit runs an average temp of 100F and It was at 144F when I got home and saw the error message.

 

[iPhil]

How many dvds you've converted since you got the machine ?


Each full content dvd done thru MTR (MacTheRipper) is usually 6-8 GB in file size.. got any other apps installed besides the 'basics'

 

[Samwise592]

There's a great free utility called "Disk Inventory X" its got a cool visual way of showing you where all your data is, and whats taking up the most space.

I use it to find large, lost files that need deleting.