Recommended free space in the system drive (c drive) for windows 2003

Hi All,

I like to know the minimum free disk space required in system driver (c drive) by windows 2003 server for normal activity. The server often gets slowed down when the disk space in system drive is less.Also, i like to know the recommended free disk space required in the system drive at any point in time for normal OS activity.

Kindly help me up

Thanks in advance

Cheers :)

Mani.