Then, only 5000/5500 is that posible? What's the difference?
The 5500 has 64mb of RAM and 16mb of Flash.
The 5600 has 32mb of RAM and 64mb of Flash.
So you can only have a maximum of 32mb of RAM with the 5600 with any image available. You can however use a swap file like most 5600 owners do to help this.
Greg