inspiron E1405 Hard Drive Full

I have 64.4GB hard drive and only 84.8MB free.  I checked installed programs and they only take up 1.92GB, I have deleted all pictures, audio, video, run defrag, disk cleanup (i have no restore points left).  I am at witts end trying to figure out where all the space is going - how do I even figure this out???  Running windows vista. 

I have searched the forum and tried everything.  I initially had this happen 6 months after I bought the computer (beginning of 2008) and they walked me through some steps, that is when I had many many pictures on the computer.  I had then put everything on an external HD and cleared out the laptop.  I have searched and searched to find a way to see if there is some way to see which files (or hidden files) use what space but I cannot figure that out!  HELP!!!!  I can only now use this computer as a netbook, I cannot even update windows as I get messages that there is not enough room on the hard drive.  any help would be greatly appreciated!!!