Ok, this is for everybody that wants to mod your 360 (flash your drive), the 360
has to be opened up. Anyway, you know that clear round case that blank CDs come in? Well that's what you'll be using to pop the thing open. Cut/break it into a small piece.

Mark off those two lines so you can break or cut it so you can actually put it to a use.

And there you have it. Then do the same thing to the other one.

Stick it in, and just put a bit of force to it, and it'll pop up, but leave that bit of plastic in, and then go do the same on the other side.

It's like magic, and you're done

That what the plastic case should look like
What you need to disassemble the thing is 1.5-2 millimeter stick and a torx screwdriver, and T10 is the size.

Here's what you have.

What you want to do now is take the face plate off.

You'll see a Microsoft sticker, which covers a gap, what you want to do is simply remove it. You'll also notice 4 clips that hold the bottom part to the top one. Make sure not to try to wedge them out, instead, gently pull outward so you can see a bit of the inside. You'll see that the side pieces connect the top to the bottom chassis. Look through the top wholes to find where the pieces connect to the white body. Grab that metal stick and it through the white holes (which are both on top and bottom of the 360) to where the pieces connect. Now slowly pull those gray pieces, and later the entire thing will release itself from the rest of the thing.

Before doing that, you must remove the harddrive. The reason why I mentioned it first is so you are familiar with the method. You can Remove the HDD by pressing that button and use the previous method, but there will be a rubber feet which you must remove so you could see where to stick the metal stick.

Make sure that your 360 is in that position, and pop the top off.

There are 12 screws, but you only need to remove the circled ones.

You're ready to flash.
tpepsiman gets the credit for the first part (the one with the case). I'm not too sure who came up with the rest of it, but it was on a forum I moderate. Anywho, because I get a lot of questions about it via Instant Messenger, I thought I'd post it here in case somebody else needs help.