1) First, use a program such as treesize (http://www.jam-software.com/treesize_free/
) to see what is using the space
2) If they are data files, you can just move them manually. If you want to move the "My Documents" folder to D:, just right click on the folder and choose "MOVE" - and then complete the action. The system will then save all future documents to the new location.
3) More likely than not, System Restore is using a HUGE amount of space. You can either reduce the space allotted to System Restore or disable it completely and start using alternative backup measures (such as disc imaging, which is highly preferable to system restore anyway). NOTE: as soon as you disable System Restore, all restore points will be IMMEDIATELY deleted.
4) Additional steps to free up space:
- If Hibernation is enabled, disable it and reboot. This will free up a large chunk of space
- Reduce space allotted to Temporary Internet Files folder
- Empty the contents of your Temp folder(s)
- Empty the Recycle Bin and reduce space allotted to the recycle bin(s)