Push up on the two tabs under the front panel (a screwdriver helps) and pull the case top toward you and then take it off. Flip the two plastic panels off to the side (one's on the right, one's on the left, the one on the right is small). Two latches hold the power supply/hard drive box in. Unlatch them and flip it over to the right. Remove the cache, VRAM, and RAM DIMMs. Disconnect the cables. If there is an AV Module in your machine, remove it. Remove the button plastic extender on the front if there is one. Take out the screw in the center of the logic board, push down on the two tabs, and slide the logic board out.
Take the case off, and remove the 3 shields in the front of the computer. Disconnect the cables from the hard drive. Pull up the clip on the back of the hard drive and push the hard drive back.
Take the case off, then lift the two tabs that hold the shield in front of the CD-ROM drive on, and remove it. Disconnect the cables from the CD-ROM drive and then pull up on the "clip" in the back of the CD-ROM drive and pull it forward.
Remove the shield in front of the CD-ROM drive, the floppy drive, and the blank one. Flip the plastic panel on the right (see the logic board steps). Disconnect the cable from the floppy drive, pull out on the two plastic panels holding the floppy drive in place, and remove it.
Information provided by Doug Brown.