If you are reffering to a 7 series, then you just need the Probe (which you can build yourself for a couple of quid) & a compatible sata chipset / PCI card. You can power your drive from the xbox, so you don't need any kind of adaptor (Regardless of what a particular troll is saying ATM). Once you have the equipment, follow THIS guide to the letter and let us know if you have any problems. You will have to update your firmware every few months or so, just to keep up with the latest security. NOTE: This is a copy and paste of a response 2 posts ago
a connectivity kit when bought will easily pay themselve on the long terme. @ miketrev I know that you have modified yours without a connectivity kit, however it is much safer than to use your Xbox 360, also it won't flag that the console had been on without SATA connection .. also I suggest you to read the Forum Rules (particularly #6) http://forums.afterdawn.com/thread_view.cfm/2487