It is entirely possible to replace the DVD Drive with a Hard Drive.
I'm going to give an example of how to use CF Cards, if you go and try SD Cards using some converter and it doesn't work, don't blame me.
What you need to do is bridge Pin 5 and 6 to Ground and supply 3.3v to Pin 7 on the DVD Drive Power Cable (The connector where the yellow cable plugs into)
After you do that, get a Molex Splitter and connect the IDE and Molex/whatever you can get 5V out of to the CF to IDE Adapter. Now the Xbox will always think that the drive is closed and it will be able to read the CF card if you have a modded Xbox and an appropriate way to access the files on the CF Card via a File Browser. It should show up as the D:/ Drive in any Dashboard.
Don't blame me if you copulate something up or it doesn't work.
