You think you should have 240 gig free; where did you come up with this number?
This will do a better job cleaning and it's built into Windows 7. Disk Cleanup : Extended
Next I would recommend looking through your computer and removing things you don't need anymore, i.e. programs, pictures ect.
Ccleaner is a good program for cleaning and removing things. I recommend staying away from registry cleaning part of the program. Their is two ways of getting more hard drive space.
1. Buying another hard drive.
2. Removing things off the drive you have.