Processor Intel® AtomTM N455 (1.66GHz/667Mhz FSB/0.5MB cache) Genuine Windows® 7 Starter 160GB4 SATA hard drive (5400RPM 1GB DDR3 SDRAM Up to 7 hours and 55 minutes of battery life with a 6-cell battery
It's all about the technology involved. Tablets have more advanced/expensive technology in them, not to mention the increased manufacturing costs. For example, looking at the two units you mentioned you the tablet has an expensive touch screen, more advanced hard drive, and more RAM.
Motherboards are the pricy parts of a tablet. Getting heat away from parts etc.. Oh and Tablets tend to have everything soldered on or integrated in the first place. Netbooks Have 1-3 Mini PCI slots
So can we conclude that tablets have a more newer technology than net tops. Once tablets become mass produced and sold, they will become cheaper in the months to come.