I have run out of free space on drive:X

Hi

I have several partitions on my Win98 machine. Some of these are quite small and about once a week I receive a message saying Drive:X is full, do I want to run disk cleanup? Does anyone know if there is a registry hack that can stop this message being displayed, or which can cause the message only to be displayed when, say, only 5MB of free space is available?

Thanks