Are you surfing the internet on the machine or downloading files?

The 9GB of usage just reflects the size of the files that your windows installation is using.

You might also check Event Viewer for errors to see if you have problems that are being logged?

How much RAM do you have assigned to the virtual machine? This will also be reflected in a file in your virtual machine directory as will any snapshots of the virtual machine that you have taken

Without more details it's hard to tell ...

ANY disk activity is a write. ANY disk writes to a growable virtual disk will expand it. Even a "delete" is NOT a delete - just an update to the directory entry for the file. For at least a short while, the actual bits of the file still exist on the hard disk (until they become overwritten by some other file). Note that this is exactly the same as a physical hard disk... just that you don't see it expand so you don't realize that it is happening.

To reclaim the space on your host which your virtual disk is using, you need to run the Shrink command within the VMware Tools for your guest.

Robert