The first picture showed it "out of the box" so the two upper covers are to be removed once you install the CD/DVD reader/writer and the floppy. But the floppy spot can be ignored in order to install a second hard-drive (for you to choose if you want to go, say, for a 180 Go HD + a floppy or 2 HD of 80Go average). I chose the second alternative as I use ADSL or CD-Burner to replace the floppy drive's most rare use as of today.
Here's a pix showing a CD-Rom once installed :
This is a pix of the bay behind the covers (the upper slot can take a CD/DVD drive and the lower can take either two HD or one HD + one 3.5 Floppy)
And here's the neat little bag provided by Shuttle if you need to carry your XPC (about EUR 30 extra). Well-made, includes steel clips for the carrying-belt (not shown here).
Basically a large photo camera bag.
Forgot to mention : the SB61G2 comes with an in-board Intel Extreme Graphis video/graphic chip taking 64Mo out of the standard Ram, so if you ain't an hard-core gamer, you can rely on it for almost everything and save an extra EUR 150-250 from a dedicated video/graphic card such as a GeForce 4/FX or an ATI Radeon.
There's also a serie called the SNxxxx which use an Nvidia NForce motherboard in combination with AMD Athlon XP processor. But I was strongly advised against it by support techies because (1) it's very noisy due to the extreme heat coming out of the AMD processor which requires the cooling system to run 100% all the time and (2) it's significantly exposed to crash/bugs/re-install because of conflicting speeds between the Ram and Bus, etc.
Basically : go for the Intel version if you aren't too comfy with tweaking/reinstalling.
And for all the Andiroo & Co furious tuners

, there's a whole range of mods available, plus tuning/overclocking options within the SB61G2 bios so you can get a few additional percent boost out the motherboard, the Ram speed, etc. Not to mention tweaking/overclocking the clocks of your video/graphic card's Memory Clock or even Core Clock.
And for the "I want my own unique look" fans, Shuttle offers a range of mods like cases, front-panels, remote controls, etc :
Eric