|If you get a generic case, you can choose one that has wiring connectors that can be used on any mboard. A new generic case without a power supply is often available cheaply locally.|
See response 3, 4, 5 in this recent Topic:
However, you may have to consult a mboard manual for a similar Asus retail mboard found on the Asus web site in order to find out what the pinouts of the headers are on your mboard are (which pin in which position is for what), if that is not shown in the mboard info I linked to.
The pinouts for the USB headers and firewire headers have been the same for all Asus models for many years, but the front panel pinouts probably vary.
Or, of course, you could just use your case as is.
You're not likely going to find the side panels for a computer as old as yours unless you search for a complete case case or case parts on the web for your model. It may be much easier to just buy another system that's the same model complete.
E.g. Your mboard is Socket 478, has a
Chipset 'North Bridge' 865G
The Asus retail model P4P800-VM is Socket 478, has a Chipset 'North Bridge' 865G, and would have been made at about the same time.
It may have all the same pinouts.
(Asus Global - Support - Downloads)
Enter P4P800-VM in the Input Model box upper left, click on Go
on the right side of that page, select