Mac Vs PC

I was curious. Exactly what parts are interchangeable between Mac’s and Pc’s. Also where can you purchase Mac parts from a third party retailer. One last thing. Can a Mac os Be installed on a blank harddrive. Kinda like a full install of windows.

Macs use standard components other than the motherboard. IDE Hard drives, CD drives, video cards and other PCI cards (even AGP 4x cards can be used in the newest models) etc etc are all the same as in PCs.
Yes of course you can install MacOS on a blank drive.
There are a variety of mac component dealers on the web, like http://www.shrevesystems.com (never used em, can’t vouch for them, I merely note they do sell a selection of mac parts). However I suspect you are asking if you can build your own Mac. Well you could, but I wouldn’t advise it, it’s not economical compared to buying new (or used) whole Mac CPUs.

Almost but not quite right. Not all third party CD-ROM drives will work with Apple’s CD-ROM driver. The other thing that won’t work right are SCSI and IDE cards. If the cards don’t know how to handle OpenFirmware (Sort of like a Mac version of a BIOS but I’m simplifing things) you won’t be able to boot off of drives attached to them. Other then those things Chas is right, RAM, Hard dirves, etc are the same between platforms.

Chas mentioned the mobo. By corollary, Macs don’t accept third party (non Apple) CPUs either. And I don’t believe that Mac CPUs are compatible w/ third party mobos.

The PowerPC CPUs are manufactured by Motorola and IBM, and since they are a completely different architecture than X86, obviously they won’t work with an X86 motherboard (They won’t fit, either, PowerPCs are pretty tiny as compared to Intel chips). There are non-Apple machines which use PowerPC processors, however.

Well, the CPUs aren’t “Apple” so much as they are Motorola or IBM. (Apple doesn’t make them). The motherboards are incompatible with 3rd-party motherboards insofar as 3rd-party motherboards are compatible with the PC platform, i.e., the set of chips and paths and digital instructions that are the descendants of the IBM PC and its clones. The Macintosh motherboard is an entirely different hardware architecture; even where it performs roughly similar actions, it accomplishes them with hardware that is often radically different.

Anyway, to continue answering the OP: many USB input devices are interchangeable, including (I believe) keyboards and mice; modems have pretty much been interchangeable for years.

Some of the best all-around sources for Mac parts are the various catalogs (MacWarehouse, MacMall, MacConnection, etc) plus the vendors listed in the back of magazines such as MacAddict and MacWorld.

The MacOS can be installed (from installer CD or just copied by dragging a viable system folder) to almost any medium that the Mac can read, as long as the medium is formatted in MacOS-native file system: hard drives, Zip cartridges, CDROMs, DVD-ROMs (I presume they are bootable, I’ve never tried it), Jaz cartridges, Orb cartridges (again, I’m assuming they are bootable), older media such as SyQuest or Bernoulli cartridges, Flopticals…possibly even flash memory cards or tape drives (I got a Mac to start booting from a Travan tape drive once but it was taking eons and I gave up on it). But of course it will only run on Macintosh hardware (unless you’ve got an emulator or something).

Fyrefiend has to be picky and bring up driver issues but I was just trying to avoid opening a can of worms. Let me just say that the components that can be used in Macs are the same as those used in PCs. Not everything has a driver.
In rereading my original statement, let me amend it a bit. I said it’s not practical to build a Mac CPU, but it is very practical to buy a relatively bare CPU and build it up yourself. My favorite site for this is http://www.xlr8yourmac.com and they have tons of info, and weird projects like people shoehorning a Mac system into an ATX case, flashing mac drivers on foreign boards, experimental disk systems, etc.

Well, I only brought up drivers for CDROMs because unlike Windows the system’s default driver only works with some drives (pretty brain dead IMO). There is CDROM Toolkit (is that even around anymore?) and a ResEdit hack to get almost all CDROMs working but that’s not for everyone (though, I used the patched driver on my PowerPC clone).