What's with all these arguments about no upgradeability? Please support your argument. But you cannot, as it's partly false.
What's missing is the pci slots. There is no other difference. I can pop a new HDD or optical drive in an emac or a imac just as easily as you can in you tower. I can't add an ADDITIONAL HDD or optical drive, but I can replace the current one with a better one. I just replaced the HDD on my Cube and I'm replacing the DVD drive with a Combo drive next week. If you know how to crack open your x86 tower to add an HDD you can do the same with a Mac. So all this talk of not being able to upgrade HDDs and optical drives on macs is horse excrement.
Added to this is the fact that other than gaming weenies (me!), the vast population of computer users just plug the damn thing in and start emailing and using Word. And they do it at work, where they use a machine they didn't choose. Then when they buy a machine for their house, they get something similar to what they have at work, Windows at work, Windows at home. The normal computer user is not going to upgrade a processor. For these people an eMac is a great machine.
Oh, and in case you didn't know, it's actually easier to upgrade the processor in a mac than it is in a PC. The way intel and AMD are going, if you want a new proc 6 months from now, you get to shell out for a new motherboard as well. With a mac, you just buy a new processor card. You're not going to get your B&W G3 to take a G5, no, but you can get the newest G3.