You can improve Windows performance by disabling the low disk space monitoring and warning message that appears when the disk space falls below the minimum specified by the system. The Percentage of low disk monitoring depends on the size of your drive. By default a 1GB hard drive is considered low at 5% and a 2GB hard drive is considered low at 2.5%. To change this, open the Registry and look for this string:
Right-click on an empty space in the right pane and select 'New->DWORD Value'. Name it 'DisableLowDiskSpaceBroadcast'. If the key already exists, double-click on it and type in '67108863' in the Decimal box then click OK.