Okay. First off, there's a handy freeware utility I would suggest you to download, as follows: http://www.piriform.com/ccleaner/download/standard
Done that, run the same and click on the 'Run Cleaner' button in the window that comes up in order to do a comprehensive cleanup of useless data in your system.
This should free up your disk space considerably.
Done that, go to Start, type in %temp%
in the search field, and press ENTER. Select and delete ALL of the contents of that folder.
Finally, if you don't use or need to use the Hibernate function (it takes up quite some space for storing the paging files in your system), you may turn it off. To do so, go to Start > All Programs > Accessories, right-click on 'Command Prompt' and select 'Run as administrator'. In the elevated command prompt that comes up, type powercfg -h off
and press Enter
Now, restart your computer accordingly.
Hope it helps. Keep me posted.