Where do I find a slimline tower case?

My video got deleted!

So here's the big issue. Some time ago, I received this computer as a Christmas present, so this computer is about 4 years old. Well, the case it was stuffed inside in got bent and the drive bay covers broke, so I took all the guts out of it and stuffed it into an old HP Pavilion tower that I had laying around. This was around the time I discovered that one of the RAM slots had become unusable, which the video will explain later. That isn't the point. Before all of the guts were moved into the cramped case, sans floppy drive, and extra cooling fans because of lack of parts, the motherboard had 4 GB of RAM installed. Makes me wonder why I had to move the memory in the first place.

I'm using a large (550w) power supply because not enough power would cause the computer to not start at all, today's graphics processors demand more power than you think. I may have to change motherboards to something else that can handle DDR3 memory and a Socket FM1 CPU. But I would much rather put it in a slim case, just thin enough and more lightweight to be placed on a wall rack. I mean seriously! My computer hutch broke as of recent and I had all this all out on the floor, and then when I got my new desk built, I had no clue where to put this crazy thing. And wiring?

This is the case I want to build my next rig in. Small compact and efficient with features beyond it's size.

Newegg.com - Thermaltake ARMOR A30 VM70001W2Z Black SECC MicroATX Mini Tower Computer Case

That's too small to fit most of anything. Check the System Specs again and see if any tower cases can support a standard ATX motherboard and 1 full-length PCI-Express x16 graphics cards. Will I have to use water-cooling instead of using this bulky Thermaltake heatsink and fan kit that had already been installed on my AMD processor? It's not like it's in danger of overheating, but the fan runs rather slow, around 1500 RPM.
My PSU has a 140mm LED fan that's mounted horizontally across the bottom and is more likely used as ventilation. In a slim tower case, can it be mounted sideways or in a position where it don't interfere with other components such as graphics cards? (This attachment should help.)

Looks like you'll need to search in the HTPC section but normally they don't allow use of big case fans but use multiple smaller fans.
Silverstone Lascala LC20M Black ATX HTPC Home Entertainment PC Case with VFD, Remote Control, Front USB, FireWire and Audio Ports LC20B-M at TigerDirect