Originally Posted by sasquatchBKP
You might need to clarify a little.
The HD on the PS3?
What exactly are you trying to download? Music? Video? A game from PSN? Where is the source? SD Card? Thumb Drive?
You say Memory Card, what kind of memory card? The PS3 uses an internal utility to create PS1/PS2 "memory cards" on the physical HD of the PS3, everything else including PS3 saved games etc are automatically stored to the HD.
Any additional info will help tailor a solution.