Well let's take a few things into account. First thing is that the manufacturer warranty on the parts you listed as the IBM based PC are MUCH longer than the default Apple Care package length.

Apple Care default = 1 year.

Hard Drives = 3-5 Years Motherboards = Depends on the company, anywhere from 1-5 years RAM = Lifetime Keyboard and Mouse = Depends on if you get it from Logitech. (basically forever)

You also miss out on upgradability by going with Apple products. You buy the computer, then you decide that hey, this computer needs to be upgraded because it has been 5 years. What parts can you upgrade from that old iMac and make it better? Answer: Hard drive and RAM only.

I would gladly pay 50 dollars less for up to five times the warranty period on some items. Futhermore I would love paying 50 dollars less for unlimited upgradability and an open system which can be utilized for gaming as well as any other task that can possibly be done on a computer.

So in regards to the price factor, I'd say that crazy warranty basically decides how many hundreds less you will be paying.

Also, in terms of reliability for iMacs: I work at a school. We have a Mac lab for tools who do web graphics design. At least 4 of those iMacs, in a small classroom of 9 iMacs, have had to have their logic boards replaced within the first year. Watching the quotes from the on site company who services them (thank god we had a good Apple Care package) was really something to laugh at. ~400 dollars for 2 DIMMs worth of ram?

What you say is deceptive too. For example, you use the iMac as a price point to compare to PCs when you should be using Mac Pro. Let's do a price rundown.

Mid-Range Mac Pro: $3,499.00

Specs: Two 2.4GHz Quad-Core Intel Xeon “Westmere”

Memory 6GB (six 1GB DIMMs) of 1066MHz DDR3 ECC SDRAM

Graphics ATI Radeon HD 5770 with 1GB GDDR5

Hard disk drive 1TB Serial ATA (3Gb/s); 7200 rpm

PCI Express Three open full-length PCI Express 2.0 expansion slots with mechanical support for 16-lane cards; 300W combined maximum for all PCI Express slots

Warranty = 1 year for everything

Similarly Configured IBM based PC: $1909.85

Processors: Intel Xeon E5620 Westmere 2.4GHz 12MB L3 Cache LGA 1366 quantity 2 ($780) (3 year warranty)

Motherboard: ASUS Z8NA-D6C Dual LGA 1366 Intel 5500 ATX Dual Intel Xeon 5500 and 5600 Series Server/Workstation Motherboard ($260) (3 year warranty) (also 3 PCIx slots too, just like mac pro)

RAM: Kingston 1GB DDR3 1333 quantity 6 ($47) (LIFETIME warranty)

Mouse: Logitech G500 ($60) (3 year warranty, also can be fucking weighted to your liking on the fly)

Keyboard: Microsoft Sidewinder x4 ($50) (warranty length unmentioned but there are videos on youtube where kids pour a whole pint glass worth of water onto one and NOTHING happens)