I have put a newer computer into an original Apple 2+ case originally made for Bell and Howell by Apple Computer Incorporated during the late 70's(Production began in 1979 and reportedly only 5000 to 10000 were made, making this Apple 2+ one of the more rarer of the Apple 2+ series; It was sold only to schools and did not come with a monitor).
I have modded this case to work of course. I had to saw off the backplane that connects the two sides of the case together, drill a few holes, and presto, a working Apple 2+ with Windows XP Professional Edition!The other funny thing; it turns on with a key, and the front power light even works, and it's even got working internal speakers!

I used a 90 watt Micro-ATX power supply(My 100 watt one is broken) and an HP Pavilion XT983 motherboard with a sound riser connector on the board which I used for the internal speakers(I did not want to fry one of my better motherboards!)
Since I did not have any extra good hard drives, I was forced to use a 10 gig hard drive which really sucks. I drilled the front hole and put a key-lock in it which I connected to the motherboard power-button connector, took some needle-nose pliars and broke off the original power light bulb, replacing it with a yellow led which I also connected to the motherboard. Then, I broke off two slats on the side of the case, took the USB riser, and screwed it to the case. Now I have two extra usb ports on the side. The power supply? I took apart the case completely so I could put it in. All I did was put it in, and screw the case tightly back together, holding it in the case like a vise.

The cd-rom drive came last: I took a long-enough screw and put the cd-rom drive on the right side of the case, screwing it to the case between the slats.
The only things I did not do: find a way to use the original keyboard and put the cd-rom drive in an original floppy drive with a long IDE and power cable.