On Windows Vista and later, you can prevent users from compressing their files in a couple of ways. First, by running the command fsutil behavior set disablecompression 1 you can disable compression on all NTFS volumes on your machine, so by deploying this command using a logon script you can disable compression on targeted users’ computers.
And second, since all the above fsutil command does is to modify NtfsDisableCompression, a REG_DWORD value found under HKLM\SYSTEM\CurrentControlSet\Control\FileSystem, this means that you could also create a custom ADMX file to deploy this registry modification using Group Policy. For more information on how to create a custom ADMX file, see KB 918239
Note that if either method is used, the registry modification doesn’t take effect until after a reboot. In addition, any previously compressed files and folders remain compressed on the machine.
Mitch Tulloch was lead author for the Windows Vista Resource Kit from Microsoft Press, which is THE book for IT pros who want to deploy, maintain and support Windows Vista in mid- and large-sized network environments. For more information see www.mtit.com.