-What comes with the case is usually a assortment of little devices. Some of these are a little intimidating but don't let it bother you. Most of the time there will be an assortment of screws, case feet, brass standoffs (support), power cord, expansion inserts, and these are really the loose stuff. Now when looking in the case you will see many bays. These bays are internal and some are hidden. The hidden bays usually support the hard drive or other devices that can mount internally like fans and so on. The upper bays in the case (Midtower) are for CD-ROM's, Floppy, Zip drives, and many more. These drives are also sold in universal sizes that already are pre-fit for the case. Most dimension's for say a internal CD-ROM are 5.25" and Floppy Drives will measure in at 3.50". So this is another consideration when buying a case. Make sure you have enough bays when it comes to future expansion.
-Also take note of the expansion slot inserts on the back of case. Make sure that there are enough for your future expansion cards. These slot usually just pop out or unscrew. Some case manufacturer's will even put a couple of extra inserts just incase you loose any.
-Power leads are another little thing to take notice of while peeking in the case. The power cords run drives, motherboards, and fans. You should have the enough power leads to correspond with the number of available drive bays not to mention a few extra for those needed upgrades in the future. When looking at these leads they are easily identified. Take a look at one of them and you will see it is keyed for one direction when inserting into a drive. Most common leads are the power lead for motherboard which is a 20 pin for the ATX and what called a p8-p9 connector for the AT case. The drive leads will be found in a 4 pin connection with the floppy drive using a 4 pin mini drive connector. The mini drive connector is used mostly for small drives like the floppy.
