1. When installing Win7, you should format the C drive before fully installing it. The newly installed 64-bit Win7 occupies about 20G of disk space. If the system is upgraded, it will occupy more disk space.

2. After the installation, use Kingsoft Internet Security's "garbage cleaning" and "system disk slimming" functions to clean the C disk;

3. Transfer all the "My Documents", "My Videos" and "My Pictures" in the "Library" outside disk C;

4. Move the cache folder in IE browser out of drive C, as follows: Click Tools in IE window-> "internet options"->; "general"->; Browse history settings-> Click the "Move Folder" button in the "Temporary Internet Files" tab (before creating a folder named "Temp" on disk D), find the "Temp" folder of disk D in the pop-up browse folder dialog box, and then press the "OK" key.

5. When installing the software, remember to change the drive letter in the installation path to a drive letter other than drive C, such as drive D (the default installation path of all software is almost always installed to drive C).

6. Clean up the disk garbage frequently to reduce the occupation of the disk by junk files.

After the above 3-6 items, the occupation of disk C can basically be maintained below 30G.