you can do the following to free up space
* use the Disk Cleanup operation on your drive. include system files as well.
* use Space Sniffer to find what files are eating up your drive. then you will know what data files can be moved.
* uninstall and reinstall to your secondary drive applications that takes up alot of space. or just change "game library" destination folder and reallocate them.
* clean up your browser downloads folder. or you can reallocate that to your secondary drive as well.