disk full on c530

If the internal disk is full on your c530, I am guessing that it is with downloaded POI's and possibly pictures. My suggestion is to remove all of the POI's and additional pictures that you have loaded onto the c530 and place them onto the SD card. The exception to that would be to keep those alerts with alarms such as the red-light file or speed traps on the c530.
On my PC I have two active files called internal and external. The Internal has the traffic files and the external has all other POI's broken into smaller folders i.e. Locations, Stores, Radio Stations. Within these folders and at the main level I have my POI files.
Using POI editior, I run it first on the internal Garmin unit using the external folder as the source, and then repeat with the internal folder to the SD card.
Assuming that you have not created new folers (other than the standard POI folder created by the editor), this action will remove your old files and replace with the new. You will still need to manually remove any of the picture files that are not needed.

On my c530, I am using 980mb and have 10.8mb free. On my SD card with over 43,000 locations loaded, I am only using 4.2mb on a 1gig card, leaving 946mb free.