This is the Antec KS-282 case. The computer case frequently ships in its own box, as shown here. Inside the case is the power cord that attaches to the power supply and a small, brown cardboard box that contains parts used to mount the motherboard inside the case.
The computer case comes with the power supply already installed, but I removed it to give you a better picture of it and to replace it with a heavier duty power supply more suitable for the video card I'm using. The small, brown cardboard box includes brass colored mounting posts as well as screws of various sizes. The screws in the lower-left corner are bracket screws. The screws in the lower-right corner are mounting post screws. The difference in size between the two is very subtle, but the bracket screws are slightly larger. The mounting posts and mounting post screws are used to mount (secure) the motherboard to the interior of the computer case.
The Antec KS-282 computer case does not come with case fans, which is fine by me since I'd rather pick out my own quiet, efficient case fans. I picked up two Sunon 80mm fans, KD1208PTB2, one for intake and one for exhaust. The fans are OEM, so they come inside a box of styrofoam chips or wrapped in bubble wrap and, in my case, bundled together with the Arctic Silver 3 I also purchased. These fans provide a reasonable amount of airflow without being annoyingly loud.
The power supply is easy to swap out (and actually, many computer cases do not include a power supply). All that's needed is to remove the screws that secure it in place, work the power supply out of the case, and insert and secure the new one with the same screws. The first picture shows the back of the Antec KS-282 where the power supply is installed (before I took it out) with the screws shown circled in red. I'm installing an Enermax EG365P-VE, which is a 365-watt power supply, as shown in the second and third pictures. Although the ATI Radeon 9800 Pro power supply recommendation allows for a 300-watt power supply and it may well work for you, it's a common precaution by savvy PC builders to go with something beefier in computers that include a video card more powerful than a GeForce4 Ti 4n00 video card.