Don't want to lose great files and don't feel like backing em' up eh? Well then here is where you should be!
Requirments:
Soft modded Xbox with UnleashX dashboard.
A FTP client I reccommend FlashFXP.
And knolledge on FTPing.
Step1. FTP to your Xbox using your FTP client
Step2. Transfer ALL the files you want to keep to your Games folder on the Xbox.
Step3. Close the FTP connection.
Step4. Turn your Xbox off.
Step5. Reformat like you usually would.
Step6. Redownload FlashFXP
Step7. FTP to your Xbox and transfer all the files from your Games folder back to your PC.
Step8. There you go, all the files you wanted back
NOTE: After the files are safely back on your computer, you may delete them from your Xbox console.
This was tested by me two days ago and it works fine.