I took apart my Max Media 4 GB Hard Drive Cartridge.
I checked out the hard drive, and on a whim, took apart my creative Zen Micro, and found it's hard drive. It's a 5Gb Seagate ST1. Uses the same ATA connector as the Max Media. I Used the Max Media 1.02 Setup installer for the new drive, plugged it into my DSLite and booted up. I had placed the moonshell .nds on the root of the drive and named it bootme.nds (thanks Datel!) I was able to listen to music and watch video with no skipping. (ROM loading works better too...)
This should even work with larger capacity drives, such as the 8Gb ST1. Anything with the ATA/IDE Plug, really.
Here's what the ST1 looks like:
And here's the magicstor:
I also want to take this time to highlight a problem I had with my Max Media Player NDS Cartridge, and what I did about it. It seems to have suffered from poor manufacturing. The "click in" slot on the side was not wide enough to work well with the NDS, and often cought in the slot. I took the cartridge and a shrp knife, and etched the slot a little wider and gave it some groves. I removed the excess plastic around the rest of the cartridge, and now it fits perfect.
Here's the best I can provide to show you what I mean:
Hopefully this will help someone. I'm also curious as to what others think of these solutions.