Win7 is improved on the basis of VISTA, so it is inevitable that drive C will take up a lot. Judging from your hard disk space, this is not the reason why your computer is slow, but because there are several ways to reduce the space used by the system disk:

One: Use vista Optimizer, which has cleaning tools to delete some system and driver backups, some unused fonts, pictures and video files, thus saving about 1G space.

Two: you can turn off the switch of the automatic reset point of the machine, which can also save a lot of space, but it is not recommended to turn it off because your machine space is still very large!

Three: Be careful not to use vista Optimizer to clean up the registry, a registry about the resource manager will be deleted by mistake!