First off, the price that they're all selling at makes a difference ...
$150 is a good price to produce a handheld which has the features consumers want but is too low of a price to produce a PC (because it is not a loss leader), and many home console owners (in particular current HD console owners) would reject a console which was so low tech.
$300 is a good price for a home console and you could build an adequate web-surfing PC, but would be too expensive to sell a handheld for and isn't enough money to build an adequate laptop.
$450 is really pushing the limit of what people will pay for a home console, is way above what people will pay for a handheld, but you could build a PC excells at productivity software or a basic web-surfing laptop.
$600 is way above what most people will pay for a home console or handheld, but is hitting a price where you can build a entry level gaming PC and a laptop good web-surfing laptop.
$750 is way above what most people will pay for a home console or handheld, but you could build a good gaming PC and a laptop which excells at productivity software.
$900 You can build a very good gaming PC and an entry level gaming laptop.
$1200 You can build a excellent gaming PC and an gaming laptop.
$1500 You can build a cutting edge gaming PC and a good gaming laptop.
$2000 You can build a bleeding edge gaming PC and an excellent gaming laptop.
