...they are. Overpriced, that is. Let's set aside FireWire, digital audio, and all that other stuff, and just focus on what people want when they buy a cheap computer. They want to go online, maybe do some digital photography, play MP3s, and burn CDs. I used to work in a computer store and that's all I heard, day in and day out.
If you want to do this on a Mac, $599 is the lowest you can go--and that's for a Mac Mini with no display, keyboard, or mouse. Or you can get a Dell for $299-$349 and it will include a display, keyboard, and mouse.
Laptops: starting bid from Apple, $1099 for a base MacBook. Dell has the Inspiron E1505 with the same specs (1.83 GHz Core Duo, 5123 MB, 60 GB, wireless, and combo drive) for $726. Not quite a washout, but it also has a 15.4" screen. A 15" MacBook Pro comes in at $1999.
Forget all about who has better hardware. service, support, OS, etc etc etc. For just the basics—a computer that can go online and do stuff--PCs are once again cheaper by far. I happen to think OS X is better than Windows XP, and I think Mac hardware is great, and I really take advantage of stuff regular consumers might not care about like FireWire and a really good built-in Terminal. But cost is cost, and PCs and Macs have once again spread quite a bit in price. Apple used to sell iMacs and iBooks for as low as $799 and the Mac Mini was originally $499, but no more—they are once again riding high, and not in a good way.