WQL - PCs with more that 2 GB free on C:
select distinct
SMS_R_System.Name,
SMS_G_System_LOGICAL_DISK.*
from
SMS_R_System inner join SMS_G_System_LOGICAL_DISK on SMS_G_System_LOGICAL_DISK.ResourceID = SMS_R_System.ResourceId
where
SMS_G_System_LOGICAL_DISK.FreeSpace > 2048
and SMS_G_System_LOGICAL_DISK.DeviceID = "C:"
order by
SMS_R_System.Name