Let me make one very important suggestion:
BACK UP YOUR ORIGINAL HARD DRIVE.. Read the guide that comes w/ slayers.
Also, just becuase you "lock" your hard drive, and even if you have a bios with build in "Live!" protection, it doesn't mean you can't get banned from Xbox live.
My suggestion is, if you EVER plan on playing on xbox live, get an xtender mod (
www.teamxtender.com). Yes, it adds some height to your xbox, but allows you to install up to 3 hard drives (120 gig or less), and boot from the one you wish using the included panel. Your best bet not to get banned is to use your retail hard drive ONLY for retail xbox stuff, and use the other hard drive(s) for non-retail stuff.
www.xbox-scene.com has more info on this if you read the forums, but you're going to wade through 1 million posts about "How come I'm not banned then if I modded with my original drive?" "I don't know, but I did everything I was supposed to and I got banned", etc etc etc. The fact is, noone is 100% positive about what new criteria Microsoft is using to detect modded xboxes, so to be safe, get a mod that allows multiple hard drives, and leave your virgin drive just the way it is.
If you don't care about/Aren't ever going to use Live!, then, don't worry about it

.
--NipsMG