I am not sure this could be of any help to you but we are working quite a lot with images and saw in an early state that keeping the images on the NS server would not be dooable. We store all of our images on a centralized storage which we connect via iSCSI to the 'C:\Program Files\Altiris\Altiris Agent\Agents\Deployment\Task Handler\image' directory. This also gives us all the features direct from the storage such as better performance, security, compression, deduplication.