Paris Hilton
So your dad liked it? To say that it looks like it was installed when the house was built is a compliment, at least, thats how I'll take it.
You can definately do the same thing with a 24" iMac, infact, of the intel iMac's, ONLY the 24" is mountable. Check the apple store for a VESA mount kit for your 24".
I hope I don't sound mean, but all information on the install is well covered in this thread, most of it in Post #1. (equipment used)
I've even just recently uploaded a PDF doco (link on post #1) with instructions and equipment used.
Obviously it will be different for everyone, I believe most homes in America are drywall/stud style (not solid brick). But hey, I dont know... In this case, the screws that come with the mount will suit. The wall mount I purchased had instructions included for a drywall/stud installation.
I've drilled a lot of holes in my house and installed a load of stuff, so I guess I'm familiar with what mounting hardware to use.
Last weekend I fitted a 20mtr garden hose reel to the back of the house. It's wild, it auto-retracts, and just looks neat. For the past few months I've been dragging a garden hose in/out of the garage (packing it away) because our puppy will just chew anything in it's path. The new enclosed reel is installed around 6ft off the ground, well out of puppy reach, and the added bonus is the hose is kept away from the elements, so should last a good while.
hang on... why am I talking about garden hoses again?
Wall mounting things sometimes doesn't go as planned. I have some coat/hat rack's in our entrance of the house which are slowly coming away from the wall. Perhaps the wall plugs are substandard, or the wrong size, eitherway, I'll need to look at that again soon. You sure wouldnt want your iMac coming away from the wall now would you? You may get woken up at 2am by the sound of a loud crash. Just the thought makes me cringe!
Always keep an eye on anything that you wall mount! (Especially if it's mounted above a floor thats covered with Italian tiles)

hehehe