Hard drive caddy/rail/bracket used in Dell's 3.5" internal bay?

I already have two hard drives in my Dimension 4700 but could definitely use another HDD.

Can the 3.5" floppy drive bay house a standard 3.5" hard drive? What kind of bracket do you need to do that? I took out the floppy drive, which I don't think I've used for the last 4 years, and tried to substitute a 3.5" hard drive in its place, but the screw holes in the floppy drive bracket would not coincide with the screw holes on the HDD.

I can easily get brackets for a standard 3.5" hard drive at a retail computer shop, but will such bracket be compatible with my Dimension 4700 case? Dell makes many parts proprietary, so I'm worried that the 3.5" floppy drive bay in Dimension 4700 was designed to be used only for Dell-branded floppy drives.

Any thoughts or experiences? Is there a hard drive caddy/rail/bracket that can fit a 3.5" HDD into Dell's proprietary 3.5" internal bay?