When your system crashes or an application crashes Windows XP/Vista the Operating System creates a dump file that can be taken into order to examine the status of the program at the time of the crash.

For general home users this cannot be of much use and waste of memory, Here’s how you can disable this option and save memory.

1. Right Click on My Computer and click “Properties” 
   [or] Windows + Pause/Break
2. Select the “Advanced Tab” and click on Setting under Startup and Recovery tab,
3. From the drop-down menu under “Write Debugging Information” Select “NONE” [ 1, in the image below ], you can also deselect “Automatic Restart” under “System failure” to prevent your computer from automatically restarting in the event of System Failure.
4. Now there won’t be anymore memory dumps and you can use the HDD Space.