This model is pretty easy to open up. To get the cover off, press the tabs up on the back cover and tilt the cover up and out. One tab is shown in the next picture.
Then you can remove it. Next you need to remove the power supply. Remove the screw that holds it in - it (along with the power supply) is shown in the next picture.
Push the floppy drive forward a bit.
Next, you need to disconnect the cables - the power cables going to the hard drive, CD-ROM drive, and the main power cable going to the logic board. The main power cable is shown here.
Slide the power supply forward as shown in the next picture.
Tilt it up and out to remove it.
If you need to actually remove the logic board, remove the screw from the "peg" mounted on the logic board, and then remove the peg.
Take out the screw that is at the front of the logic board as well. Disconnect the cables from the logic board. Two of them are shown in the next picture.
Slide the hard drive and CD-ROM drives forward and remove them by pressing down on the tabs, also remove the floppy drive. For detailed information on removing them see the hard drive, floppy drive, and CD-ROM drive sections. Slide the logic board forward and remove it.
Remove the metal shield in front of the hard drive.
Disconnect the cables from the back of it, press down on the tab, and slide the hard drive forward.
Disconnect the cables from the back of drive, pull up on the tab, and slide the CD-ROM drive out.
Pull out the tabs that hold the floppy drive in, slide it out a bit, disconnect the floppy cable, and slide it out all the way.
Information and pictures provided by Doug Brown.