TeamXbox has the goods on Datel's Xbox360 Transfer Kit available
Datel's Transfer Kit for Xbox 360 allows you to transfer data from your Xbox 360 memory cards to your PC. By using your PC's storage capacity to hold almost unlimited back-up 'images' of your Xbox 360 memory cards, you can archive and restore them at any time – you need never be short of save space again.
Backing up your memory card couldn't be simpler. Using your Transfer Kit PC application and USB dock, you can save the entire contents of your XB360 memory card to your computer's hard drive as an 'image' file. Each image file automatically logs the time and date of backup, and you can add your own descriptions and file names, so you always know what's where.
It's just as simple to restore an image file to your memory card too. Again using the PC application, just click on the 'Hard Drive' blade and you're shown a list of backed-up memory card images, replete with the date and time at which they were saved and the name and description entered when you backed up. Just plug in your USB dock and an XB360 memory card, and you can restore the image file to the card and use the saves in your console once more.
When you've archived your memory card, you can email the backed-up image to your friends and share your saves with friends from all over the world. As long as the save or file is not locked to your own console or Xbox Live account, they can then use their own Transfer Kit to unpack it onto a memory card and use it themselves.
A little more mainstream than homebrew Sata connections. How many people (core system owners?) will pick this up for $15?