How do you manage free space for Oracle on NT?

Our DBA team has a goal to let the tablespace grow as long as each datafile is below 2GB. What we did is setting the autoextend on for all tablespaces and watch the free space on the OS level very closely. As long as the disk space is less than 90% full, we are fine. Currently, we monitor the free space by watching the free space on the "Windows Explorer." This is something I think we can improve.

Question: Is there a way to write a script on the OS level to check the disk space usage info? On unix, I can use "df -k." Do you have any suggestion on NT? Thanks!